Method for transmitting/receiving signal in wireless communication system, and device supporting same

ABSTRACT

Disclosed in various embodiments are a method for transmitting/receiving a signal in a wireless communication system, and a device supporting same. More particularly, disclosed in various embodiments are a method for transmitting/receiving a synchronization signal block (SSB) in an unlicensed band, and a device supporting same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/267,446, filed on Feb. 9, 2021, which is the National Phase of PCTInternational Application No. PCT/KR2019/010103, filed on Aug. 9, 2019,which claims priority to Korean Patent Application Nos. 10-2018-0092796,filed on Aug. 9, 2018, 10-2019-0003563, filed on Jan. 10, 2019,10-2019-0007410, filed on Jan. 21, 2019, 10-2019-0018193, filed on Feb.15, 2019, 10-2019-0035564, filed on Mar. 28, 2019, and 10-2019-0051526,file don May 2, 2019. The disclosures of the prior applications areincorporated by reference in their entirety.

TECHNICAL FIELD

Various embodiments of the present disclosure relate to a wirelesscommunication system, and more particularly, to a method and apparatusfor transmitting and receiving a signal in a wireless communicationsystem.

BACKGROUND

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, awireless access system is a multiple access system that supportscommunication of multiple users by sharing available system resources (abandwidth, transmission power, etc.) among them. For example, multipleaccess systems include a Code Division Multiple Access (CDMA) system, aFrequency Division Multiple Access (FDMA) system, a Time DivisionMultiple Access (TDMA) system, an Orthogonal Frequency Division MultipleAccess (OFDMA) system, and a Single Carrier Frequency Division MultipleAccess (SC-FDMA) system.

As a number of communication devices have required higher communicationcapacity, the necessity of the mobile broadband communication muchimproved than the existing radio access technology (RAT) has increased.In addition, massive machine type communications (MTC) capable ofproviding various services at anytime and anywhere by connecting anumber of devices or things to each other has been considered in thenext generation communication system. Moreover, a communication systemdesign capable of supporting services/UEs sensitive to reliability andlatency has been discussed.

As described above, the introduction of the next generation RATconsidering the enhanced mobile broadband communication, massive MTC,Ultra-reliable and low latency communication (URLLC), and the like hasbeen discussed.

SUMMARY

Various embodiments of the present disclosure may provide a method andapparatus for transmitting and receiving signals in a wirelesscommunication system.

Specifically, various embodiments of the present disclosure may providea method and apparatus for transmitting and receiving a synchronizationsignal block (SSB) in an unlicensed band in consideration of the featureof the unlicensed band in which a channel access procedure (CAP) shouldbe performed before signal transmission and reception.

Further, various embodiments of the present disclosure may provide amethod and apparatus for transmitting and receiving a radio resourcemanagement (RRM) report based on an SSB transmitted and received in anunlicensed band.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Various embodiments of the present disclosure may provide a method andapparatus for transmitting a signal in a wireless communication system.

According to various embodiments of the present disclosure, a method oftransmitting a signal by an apparatus in a wireless communication systemmay be provided. The method may include performing a channel accessprocedure (CAP) for an unlicensed band, and transmitting one or moresynchronization signal blocks (SSBs) in the unlicensed band based on theCAP.

In an exemplary embodiment, the one or more SSBs may be transmitted onone or more consecutive second candidate positions including a startingcandidate position determined based on the CAP among first candidatepositions configured within a time window.

In an exemplary embodiment, indexes from 0 to N−1 may be repeatedlyassigned to the first candidate positions.

In an exemplary embodiment, N may be the number of the one or more SSBs,and the indexes of the one or more SSBs may be identical to the indexesof the one or more second candidate positions, respectively.

In an exemplary embodiment, wherein based on a first SSB among the oneor more SSBs not being available to be transmitted on the one or moresecond candidate positions according to the position of the startingcandidate position determined based on the CAP, transmission of the oneor more SSBs may be dropped, the remaining one or more second SSBs amongthe one or more SSBs may be transmitted on the one or more secondcandidate positions while transmission of the first SSB may be dropped,or the one or more second SSBs may be transmitted on the one or moresecond candidate positions while the first SSB may be transmitted in atime area outside the time window, contiguously to the one or moresecond SSBs.

In an exemplary embodiment, the first candidate positions may bedetermined based on a minimum time interval on which a SSB related tothe same beam index or a SSB with a quasi-co-located (QCL) relationshipis available to be transmitted.

In an exemplary embodiment, the method may further include transmittinginformation about the minimum time interval by cell-specific radioresource control (RRC) signaling or user equipment (UE)-specific RRCsignaling.

In an exemplary embodiment, the minimum time interval may be determinedto be one of preconfigured limited values.

In an exemplary embodiment, the information about the minimum timeinterval may be related to one or more bits included in thecell-specific RRC signaling or the UE-specific RRC signaling, and theone value may be indicated based on a value of the one or more bits.

In an exemplary embodiment, the method may further include transmittingthe information about the minimum time interval for each cell identifier(ID) by cell-specific RRC signaling, system information block 3 (SIB 3),or SIB4, and receiving information related to radio resource management(RRM) measurement for a neighboring cell in response to the informationabout the minimum time interval for each cell ID.

In an exemplary embodiment, the information related to RRM measurementmay be configured for each of the first candidate positions.

According to various embodiments of the present disclosure, an apparatusfor transmitting a signal in a wireless communication system may beprovided. The apparatus may include at least one memory, and at leastone processor coupled to the at least one memory. The at least oneprocessor may be configured to perform a CAP for an unlicensed band, andtransmit one or more SSBs in the unlicensed band based on the CAP.

In an exemplary embodiment, the one or more SSBs may be transmitted onone or more consecutive second candidate positions including a startingcandidate position determined based on the CAP among first candidatepositions configured within a time window.

In an exemplary embodiment, the first candidate positions may bedetermined based on a minimum time interval on which a SSB related tothe same beam index or a SSB with a quasi-co-located (QCL) relationshipis available to be transmitted.

In an exemplary embodiment, the at least one processor may be configuredto transmit information about the minimum time interval by cell-specificRRC signaling or UE-specific RRC signaling.

According to various embodiments of the present disclosure, an apparatusfor receiving a signal in a wireless communication system may beprovided. The apparatus may include at least one memory and at least oneprocessor coupled to the at least one memory. The at least one processormay be configured to receive one or more SSBs in an unlicensed bandbased on a CAP for the unlicensed band.

In an exemplary embodiment, the one or more SSBs may be received at oneor more consecutive second candidate positions including a startingcandidate position determined based on the CAP among first candidatepositions configured within a time window.

In an exemplary embodiment, the apparatus may communicate at least oneof a mobile terminal, a network, or an autonomous driving vehicle otherthan a vehicle including the apparatus.

The above-described various embodiments of the present disclosure areonly some of the preferred embodiments of the present disclosure, andvarious embodiments reflecting the technical features of the presentdisclosure may be derived and understood from the following detaileddescription of the present disclosure by those skilled in the art.

According to various embodiments of the present disclosure, thefollowing effects may be achieved.

According to various embodiments of the present disclosure, a method andapparatus for transmitting and receiving a synchronization signal block(SSB) in an unlicensed band in consideration of the feature of theunlicensed band in which a channel access procedure (CAP) should beperformed before signal transmission and reception may be provided.

Specifically, according to various embodiments of the presentdisclosure, a method and apparatus for transmitting and receiving asynchronization signal block (SSB) in an unlicensed band may beprovided, which eliminate ambiguity of a user equipment (UE) about anunspecified starting time of an SSB transmission in view of the featureof the unlicensed band in which signal transmission and receptiondepends on a channel access procedure (CAP).

Further, according to various embodiments of the present disclosure, amethod and apparatus for transmitting and receiving a radio resourcemanagement (RRM) report based on an SSB transmitted and received in theabove-described unlicensed band may be provided.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present disclosure, provide embodiments of thepresent disclosure together with detail explanation. Yet, a technicalcharacteristic of the present disclosure is not limited to a specificdrawing. Characteristics disclosed in each of the drawings are combinedwith each other to configure a new embodiment. Reference numerals ineach drawing correspond to structural elements.

FIG. 1 is a diagram illustrating physical channels and a signaltransmission method using the physical channels, which may be used invarious embodiments of the present disclosure;

FIGS. 2A and 2B are diagrams illustrating a radio frame structure in along term evolution (LTE) system to which various embodiments of thepresent disclosure are applicable;

FIG. 3 is a diagram illustrating a radio frame structure in an LTEsystem to which various embodiments of the present disclosure areapplicable;

FIG. 4 is a diagram illustrating a slot structure in an LTE system towhich various embodiments of the present disclosure are applicable;

FIG. 5 is a diagram illustrating an uplink (UL) subframe structure in anLTE system to which various embodiments of the present disclosure areapplicable;

FIG. 6 is a diagram illustrating a downlink (DL) subframe structure inan LTE system to which various embodiments of the present disclosure areapplicable;

FIG. 7 is a diagram illustrating a radio frame structure in a new radioaccess technology (NR) system to which various embodiments of thepresent disclosure are applicable;

FIG. 8 is a diagram illustrating a slot structure in an NR system towhich various embodiments of the present disclosure are applicable;

FIG. 9 is a diagram illustrating a self-contained slot structure towhich various embodiments of the present disclosure are applicable;

FIG. 10 is a diagram illustrating the structure of one resource elementgroup (REG) in an NR system to which various embodiments of the presentdisclosure are applicable;

FIG. 11 is a diagram illustrating representative methods of connectingtransceiver units (TXRUs) to antenna elements according to variousembodiments of the present disclosure;

FIG. 12 is a diagram illustrating representative methods of connectingTXRUs to antenna elements according to various embodiments of thepresent disclosure;

FIG. 13 is a schematic diagram illustrating a hybrid beamformingstructure from the perspective of TXRUs and physical antennas accordingto various embodiments of the present disclosure;

FIG. 14 is a schematic diagram illustrating a beam sweeping operationfor a synchronization signal and system information in a downlinktransmission procedure according to various embodiments of the presentdisclosure;

FIG. 15 is a schematic diagram illustrating a synchronizationsignal/physical broadcast channel (SS/PBCH) block applicable to variousembodiments of the present disclosure;

FIG. 16 is a schematic diagram illustrating an SS/PBCH blocktransmission configuration applicable to various embodiments of thepresent disclosure;

FIGS. 17A and 17B illustrate an exemplary wireless communication systemsupporting an unlicensed band, which is applicable to variousembodiments of the present disclosure;

FIG. 18 is a diagram illustrating a channel access procedure (CAP) fortransmission in an unlicensed band, which is applicable to variousembodiments of the present disclosure;

FIG. 19 is a diagram illustrating a partial transmission time interval(TTI) or a partial subframe/slot, which is applicable to variousembodiments of the present disclosure;

FIG. 20 is a simplified diagram illustrating a signal flow foroperations of a user equipment (UE) and a base station (BS) in anunlicensed band to which various embodiments of the present disclosureare applicable;

FIG. 21 is a diagram illustrating an exemplary synchronization signalblock (SSB) transmission structure according to various embodiments ofthe present disclosure;

FIG. 22 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure;

FIG. 23 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure;

FIG. 24 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure;

FIG. 25 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure;

FIG. 26 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure;

FIG. 27 is a simplified diagram illustrating a signal flow for aninitial network access and subsequent communication process according tovarious embodiments of the present disclosure;

FIG. 28 is a simplified diagram illustrating a signal flow for a methodof operating a UE and a BS according to various embodiments of thepresent disclosure;

FIG. 29 is a flowchart illustrating a method of operating a UE accordingto various embodiments of the present disclosure;

FIG. 30 is a flowchart illustrating a method of operating a BS accordingto various embodiments of the present disclosure;

FIG. 31 is a block diagram illustrating an apparatus for implementingvarious embodiments of the present disclosure;

FIG. 32 is a diagram illustrating a communication system to whichvarious embodiments of the present disclosure are applicable;

FIG. 33 is a block diagram illustrating wireless devices to whichvarious embodiments of the present disclosure are applicable;

FIG. 34 is a block diagram illustrating another example of wirelessdevices to which various embodiments of the present disclosure areapplicable;

FIG. 35 is a block diagram illustrating a portable device applied tovarious embodiments of the present disclosure; and

FIG. 36 is a block diagram illustrating a vehicle or an autonomousdriving vehicle, which is applied to various embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The various embodiments of the present disclosure described below arecombinations of elements and features of the various embodiments of thepresent disclosure in specific forms. The elements or features may beconsidered selective unless otherwise mentioned. Each element or featuremay be practiced without being combined with other elements or features.Further, various embodiments of the present disclosure may beconstructed by combining parts of the elements and/or features.Operation orders described in various embodiments of the presentdisclosure may be rearranged. Some constructions or elements of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions or features of another embodiment.

In the description of the attached drawings, a detailed description ofknown procedures or steps of the various embodiments of the presentdisclosure will be avoided lest it should obscure the subject matter ofthe various embodiments of the present disclosure. In addition,procedures or steps that could be understood to those skilled in the artwill not be described either.

Throughout the specification, when a certain portion “includes” or“comprises” a certain component, this indicates that other componentsare not excluded and may be further included unless otherwise noted. Theterms “unit”, “-or/er” and “module” described in the specificationindicate a unit for processing at least one function or operation, whichmay be implemented by hardware, software or a combination thereof. Inaddition, the terms “a or an”, “one”, “the” etc. may include a singularrepresentation and a plural representation in the context of the variousembodiments of the present disclosure (more particularly, in the contextof the following claims) unless indicated otherwise in the specificationor unless context clearly indicates otherwise.

In the various embodiments of the present disclosure, a description ismainly made of a data transmission and reception relationship between aBase Station (BS) and a User Equipment (UE). A BS refers to a terminalnode of a network, which directly communicates with a UE. A specificoperation described as being performed by the BS may be performed by anupper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with a fixed station, aNode B, an evolved Node B (eNode B or eNB), gNode B (gNB), an advancedbase station (ABS), an access point, etc.

In the various embodiments of the present disclosure, the term terminalmay be replaced with a UE, a mobile station (MS), a subscriber station(SS), a mobile subscriber station (MSS), a mobile terminal, an advancedmobile station (AMS), etc.

A transmission end is a fixed and/or mobile node that provides a dataservice or a voice service and a reception end is a fixed and/or mobilenode that receives a data service or a voice service. Therefore, a UEmay serve as a transmission end and a BS may serve as a reception end,on an uplink (UL). Likewise, the UE may serve as a reception end and theBS may serve as a transmission end, on a downlink (DL).

The various embodiments of the present disclosure may be supported bystandard specifications disclosed for at least one of wireless accesssystems including an institute of electrical and electronics engineers(IEEE) 802.xx system, a 3rd generation partnership project (3GPP)system, a 3GPP long term evolution (LTE) system, 3GPP 5G NR system and a3GPP2 system. In particular, the various embodiments of the presentdisclosure may be supported by the standard specifications, 3GPP TS36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321, 3GPP TS 36.331,3GPP TS 37.213, 3GPP TS 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS38.321 and 3GPP TS 38.331. That is, the steps or parts, which are notdescribed to clearly reveal the technical idea of the variousembodiments of the present disclosure, in the various embodiments of thepresent disclosure may be explained by the above standardspecifications. All terms used in the various embodiments of the presentdisclosure may be explained by the standard specifications.

Reference will now be made in detail to the various embodiments of thepresent disclosure with reference to the accompanying drawings. Thedetailed description, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present disclosure, rather than to show the only embodiments thatcan be implemented according to the disclosure.

The following detailed description includes specific terms in order toprovide a thorough understanding of the various embodiments of thepresent disclosure. However, it will be apparent to those skilled in theart that the specific terms may be replaced with other terms withoutdeparting the technical spirit and scope of the various embodiments ofthe present disclosure.

Hereinafter, 3GPP LTE/LTE-A systems and 3GPP NR system are explained,which are examples of wireless access systems.

The various embodiments of the present disclosure can be applied tovarious wireless access systems such as code division multiple access(CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), orthogonal frequency division multiple access(OFDMA), single carrier frequency division multiple access (SC-FDMA),etc.

CDMA may be implemented as a radio technology such as universalterrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented asa radio technology such as global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). OFDMA may be implemented as a radio technology such asIEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA(E-UTRA), etc.

UTRA is a part of universal mobile telecommunications system (UMTS).3GPP LTE is a part of evolved UMTS (E-UMTS) using E-UTRA, adopting OFDMAfor DL and SC-FDMA for UL. LTE-advanced (LTE-A) is an evolution of 3GPPLTE.

While the various embodiments of the present disclosure are described inthe context of 3GPP LTE/LTE-A systems and 3GPP NR system in order toclarify the technical features of the various embodiments of the presentdisclosure, the various embodiments of the present disclosure is alsoapplicable to an IEEE 802.16e/m system, etc.

1. Overview of 3GPP System

1.1. Physical Channels and General Signal Transmission

In a wireless access system, a UE receives information from a basestation on a DL and transmits information to the base station on a UL.The information transmitted and received between the UE and the basestation includes general data information and various types of controlinformation. There are many physical channels according to thetypes/usages of information transmitted and received between the basestation and the UE.

FIG. 1 is a diagram illustrating physical channels and a signaltransmission method using the physical channels, which may be used invarious embodiments of the present disclosure.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to a BS. Specifically, the UE synchronizes its timing tothe base station and acquires information such as a cell identifier (ID)by receiving a primary synchronization channel (P-SCH) and a secondarysynchronization channel (S-SCH) from the BS.

Then the UE may acquire information broadcast in the cell by receiving aphysical broadcast channel (PBCH) from the base station.

During the initial cell search, the UE may monitor a DL channel state byreceiving a downlink reference signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a physical downlink control channel (PDCCH) andreceiving on a physical downlink shared channel (PDSCH) based oninformation of the PDCCH (S12).

Subsequently, to complete connection to the eNB, the UE may perform arandom access procedure with the eNB (S13 to S16). In the random accessprocedure, the UE may transmit a preamble on a physical random accesschannel (PRACH) (S13) and may receive a PDCCH and a random accessresponse (RAR) for the preamble on a PDSCH associated with the PDCCH(S14). The UE may transmit a PUSCH by using scheduling information inthe RAR (S15), and perform a contention resolution procedure includingreception of a PDCCH signal and a PDSCH signal corresponding to thePDCCH signal (S16).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the BS (S17) and transmit a physical uplink shared channel (PUSCH)and/or a physical uplink control channel (PUCCH) to the BS (S18), in ageneral UL/DL signal transmission procedure.

Control information that the UE transmits to the BS is genericallycalled uplink control information (UCI). The UCI includes a hybridautomatic repeat and request acknowledgement/negative acknowledgement(HARQ-ACK/NACK), a scheduling request (SR), a channel quality indicator(CQI), a precoding matrix index (PMI), a rank indicator (RI), etc.

In general, UCI is transmitted periodically on a PUCCH. However, ifcontrol information and traffic data should be transmittedsimultaneously, the control information and traffic data may betransmitted on a PUSCH. In addition, the UCI may be transmittedaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

1.2. Radio Frame Structures

FIGS. 2 and 3 illustrate radio frame structures in an LTE system towhich various embodiments of the present disclosure are applicable.

The LTE system supports frame structure type 1 for frequency divisionduplex (FDD), frame structure type 2 for time division duplex (TDD), andframe structure type 3 for an unlicensed cell (UCell). In the LTEsystem, up to 31 secondary cells (SCells) may be aggregated in additionto a primary cell (PCell). Unless otherwise specified, the followingoperation may be applied independently on a cell basis.

In multi-cell aggregation, different frame structures may be used fordifferent cells. Further, time resources (e.g., a subframe, a slot, anda subslot) within a frame structure may be generically referred to as atime unit (TU).

FIG. 2A illustrates frame structure type 1. Frame type 1 is applicableto both a full Frequency Division Duplex (FDD) system and a half FDDsystem.

A DL radio frame is defined by 10 1-ms subframes. A subframe includes 14or 12 symbols according to a cyclic prefix (CP). In a normal CP case, asubframe includes 14 symbols, and in an extended CP case, a subframeincludes 12 symbols.

Depending on multiple access schemes, a symbol may be an OFDM(A) symbolor an SC-FDM(A) symbol. For example, a symbol may refer to an OFDM(A)symbol on DL and an SC-FDM(A) symbol on UL. An OFDM(A) symbol may bereferred to as a cyclic prefix-OFDMA(A) (CP-OFDM(A)) symbol, and anSC-FMD(A) symbol may be referred to as a discrete Fouriertransform-spread-OFDM(A) (DFT-s-OFDM(A)) symbol.

One subframe may be defined by one or more slots according to asubcarrier spacing (SCS) as follows.

-   -   When SCS=7.5 kHz or 15 kHz, subframe #i is defined by two 0.5-ms        slots, slot #2i and slot #2i+1 (i=0˜9).    -   When SCS=1.25 kHz, subframe #i is defined by one 1-ms slot, slot        #2i.    -   When SCS=15 kHz, subframe #i may be defined by six subslots as        illustrated in Table 1.

Table 1 lists exemplary subslot configurations for one subframe (normalCP).

TABLE 1 Subslot number 0 1 2 3 4 5 Slot number 2i 2i + 1 Uplink subslot0, 1, 2 3, 4 5, 6 0, 1 2, 3 4, 5, 6 Pattern (Symbol number) Downlinksubslot 0, 1, 2 3, 4 5, 6 0, 1 2, 3 4, 5, 6 Pattern 1 (Symbol number)Downlink subslot 0, 1 2, 3, 4 5, 6 0, 1 2, 3 4, 5, 6 Pattern 2 (Symbolnumber)

FIG. 2B illustrates frame structure type 2. Frame structure type 2 isapplied to a TDD system. Frame structure type 2 includes two halfframes. A half frame includes 4 (or 5) general subframes and 1 (or 0)special subframe. According to a UL-DL configuration, a general subframeis used for UL or DL. A subframe includes two slots.

Table 2 lists exemplary subframe configurations for a radio frameaccording to UL-DL configurations.

TABLE 2 Uplink- Downlink- downlink to-Uplink configura- Switch PointSubframe number tion Periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 2, D represents a DL subframe, U represents a UL subframe, andS represents a special subframe. A special subframe includes a downlinkpilot time slot (DwPTS), a guard period (GP), and an uplink pilot timeslot (UpPTS). The DwPTS is used for initial cell search,synchronization, or channel estimation at a UE. The UpPTS is used forchannel estimation at an eNB and acquisition of UL transmissionsynchronization at a UE. The GP is a period for cancelling interferenceof a UL caused by the multipath delay of a DL signal between a DL andthe UL.

Table 3 lists exemplary special subframe configurations.

TABLE 3 Normal cyclic Prefix in downlink UpPTS Extended cyclic Prefix indownlink Special Normal cyclic Extended cyclic UpPTS subframe PrefixPrefix Normal cyclic Extended cyclic configuration DwPTS in uFlink inuFlink DwPTS Prefix in uplink Prefix in uplink 0  6592 · T_(s) (1 + X) ·(1 + X) · 2560 · T_(s)  7680 · T_(s) (1 + X) · (1 + X) · 1 19760 · T_(s)2192 · T_(s) 20480 · T_(s) 2192 · T_(s) 2560 · T_(s) 2 21952 · T_(s)23040 · T_(s) 3 24144 · T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 ·T_(s) (2 + X) · (2 + X) · 5  6592 · T_(s) (2 + X) · (2 + X) · 2560 ·T_(s) 20480 · T_(s) 2192 · T_(s) 2560 · T_(s) 6 19760 · T_(s) 2192 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — — 10 13168 · T_(s) 13152 · T_(s) 12800 · T_(s) — — —

In Table 3, X is configured by higher-layer signaling (e.g., radioresource control (RRC) signaling or the like) or given as 0.

FIG. 3 is a diagram illustrating frame structure type 3.

Frame structure type 3 may be applied to a UCell operation. Framestructure type 3 may be applied to, but not limited to, a licensedassisted access (LAA) SCell with a normal CP. A frame is 10 ms induration, including 10 1-ms subframes. Subframe #i is defined by twoconsecutive slots, slot #2i and slot #2i+1. Each subframe in a frame maybe used for a DL or UL transmission or may be empty. A DL transmissionoccupies one or more consecutive subframes, starting from any time in asubframe and ending at a boundary of a subframe or in a DwPTS of Table3. A UL transmission occupies one or more consecutive subframes.

FIG. 4 is a diagram illustrating a slot structure in an LTE system towhich various embodiments of the present disclosure are applicable.

Referring to FIG. 4 , a slot includes a plurality of orthogonalfrequency division multiplexing (OFDM) symbols in the time domain by aplurality of resource blocks (RBs) in the frequency domain. A symbol mayrefer to a symbol duration. A slot structure may be described by aresource grid including N^(DL/UL) _(RB)N^(RB) _(sc) subcarriers andN^(DL/UL) _(symb) symbols. N^(DL) _(RB) represents the number of RBs ina DL slot, and N^(UL) _(RB) represents the number of RBs in a UL slot.N^(DL) _(RB) and N^(UL) _(RB) are dependent on a DL bandwidth and a ULbandwidth, respectively. N^(DL) _(symb) represents the number of symbolsin the DL slot, and N^(UL) _(symb) represents the number of symbols inthe UL slot. N^(RB) _(sc) represents the number of subcarriers in oneRB. The number of symbols in a slot may vary according to an SCS and aCP length (see Table 1). For example, while one slot includes 7 symbolsin a normal CP case, one slot includes 6 symbols in an extended CP case.

An RB is defined as N^(DL/UL) _(symb) (e.g., 7) consecutive symbols inthe time domain by N^(RB) _(sc) (e.g., 12) consecutive subcarriers inthe frequency domain. The RB may be a physical resource block (PRB) or avirtual resource block (VRB), and PRBs may be mapped to VRBs in aone-to-one correspondence. Two RBs each being located in one of the twoslots of a subframe may be referred to as an RB pair. The two RBs of anRB pair may have the same RB number (or RB index). A resource with onesymbol by one subcarrier is referred to as a resource element (RE) ortone. Each RE in the resource grid may be uniquely identified by anindex pair (k, l) in a slot. k is a frequency-domain index ranging from0 to N^(DL/UL) _(RB)×N^(RB) _(sc)−l and l is a time-domain index rangingfrom 0 to N^(DL/UL) _(symb)−1.

FIG. 5 is a diagram illustrating a UL subframe structure in an LTEsystem to which various embodiments of the present disclosure areapplicable.

Referring to FIG. 5 , one subframe 500 includes two 0.5-ms slots 501.Each slot includes a plurality of symbols 502, each corresponding to oneSC-FDMA symbol. An RB 503 is a resource allocation unit corresponding to12 subcarriers in the frequency domain by one slot in the time domain.

A UL subframe is divided largely into a control region 504 and a dataregion 505. The data region is communication resources used for each UEto transmit data such as voice, packets, and so on, including a physicaluplink shared channel (PUSCH). The control region is communicationresources used for each UE to transmit an ACK/NACK for a DL channelquality report or a DL signal, a UL scheduling request, and so on,including a physical uplink control channel (PUCCH).

A sounding reference signal (SRS) is transmitted in the last SC-FDMAsymbol of a subframe in the time domain.

FIG. 6 is a diagram illustrating a DL subframe structure in an LTEsystem to which various embodiments of the present disclosure areapplicable.

Referring to FIG. 6 , up to three (or four) OFDM(A) symbols at thebeginning of the first slot of a subframe corresponds to a controlregion. The remaining OFDM(A) symbols correspond to a data region inwhich a PDSCH is allocated, and a basic resource unit of the data regionis an RB. DL control channels include a physical control formatindicator channel (PCFICH), a physical downlink control channel (PDCCH),a physical hybrid-ARQ indicator channel (PHICH), and so on.

The PCFICH is transmitted in the first OFDM symbol of a subframe,conveying information about the number of OFDM symbols (i.e., the sizeof a control region) used for transmission of control channels in thesubframe. The PHICH is a response channel for a UL transmission,conveying a hybrid automatic repeat request (HARQ) acknowledgement(ACK)/negative acknowledgement (NACK) signal. Control informationdelivered on the PDCCH is called downlink control information (DCI). TheDCI includes UL resource allocation information, DL resource controlinformation, or a UL transmit (Tx) power control command for any UEgroup.

FIG. 7 is a diagram illustrating a radio frame structure in an NR systemto which various embodiments of the present disclosure are applicable.

The NR system may support multiple numerologies. A numerology may bedefined by a subcarrier spacing (SCS) and a cyclic prefix (CP) overhead.Multiple SCSs may be derived by scaling a default SCS by an integer N(or μ). Further, even though it is assumed that a very small SCS is notused in a very high carrier frequency, a numerology to be used may beselected independently of the frequency band of a cell. Further, the NRsystem may support various frame structures according to multiplenumerologies.

Now, a description will be given of OFDM numerologies and framestructures which may be considered for the NR system. Multiple OFDMnumerologies supported by the NR system may be defined as listed inTable 4. For a bandwidth part, and a CP are obtained from RRC parametersprovided by the BS.

TABLE 4 Δf = 2^(μ) · 15 Cyclic μ [kHz] prefix 0  15 Normal 1  30 Normal2  60 Normal, Extended 3 120 Normal 4 240 Normal

In NR, multiple numerologies (e.g., SCSs) are supported to support avariety of 5G services. For example, a wide area in cellular bands issupported for an SCS of 15 kHz, a dense-urban area, a lower latency, anda wider carrier bandwidth are supported for an SCS of 30 kHz/60 kHz, anda larger bandwidth than 24.25 GHz is supported for an SCS of 60 kHz ormore, to overcome phase noise.

An NR frequency band is defined by two types of frequency ranges, FR1and FR2. FR1 may be a sub-6 GHz range, and FR2 may be an above-6 GHzrange, that is, a millimeter wave (mmWave) band.

Table 5 below defines the NR frequency band, by way of example.

TABLE 5 Frequency range Corresponding Subcarrier designation frequencyrange Spacing FR1  410 MHz-7125 MHz  15, 30, 60 kHz FR2 24250 MHz-52600MHz 60, 120, 240 kHz

Regarding a frame structure in the NR system, the time-domain sizes ofvarious fields are represented as multiples of a basic time unit for NR,T_(c)=1/(Δf_(max)*N_(f)) where Δf_(max)=480*10³ Hz and a value N_(f)related to a fast Fourier transform (FFT) size or an inverse fastFourier transform (IFFT) size is given as N_(f)=4096. T_(c) and T_(s)which is an LTE-based time unit and sampling time, given as T_(s)=1/((15kHz)*2048) are placed in the following relationship: T_(s)/T_(e)=64. DLand UL transmissions are organized into (radio) frames each having aduration of T_(f)=(Δf_(max)*N_(f)/100)*T_(c)=10 ms. Each radio frameincludes 10 subframes each having a duration ofT_(sf)=(Δf_(max)*N_(f)/1000)*T_(c)=1 ms. There may exist one set offrames for UL and one set of frames for DL. For a numerology p, slotsare numbered with n^(μ) _(s)∈{0, . . . , N^(slot,μ) _(subframe)−1} in anincreasing order in a subframe, and with n^(μ) _(s,f)∈{0, . . . ,N^(slot) _(frame)−1} in an increasing order in a radio frame. One slotincludes N^(μ) _(symb) consecutive OFDM symbols, and N^(μ) _(symb)depends on a CP. The start of a slot n s in a subframe is aligned intime with the start of an OFDM symbol n^(μ) _(s)*N^(μ) _(symb) in thesame subframe.

Table 6 lists the number of symbols per slot, the number of slots perframe, and the number of slots per subframe, for each SCS in a normal CPcase, and Table 7 lists the number of symbols per slot, the number ofslots per frame, and the number of slots per subframe, for each SCS inan extended CP case.

TABLE 6 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 014 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

TABLE 7 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 212 40 4

In the above tables, N^(slot) _(symb) represents the number of symbolsin a slot, N^(frame,μ) _(slot) represents the number of slots in aframe, and N^(subframe) _(slot) represents the number of slots in asubframe.

In the NR system to which various embodiments of the present disclosureare applicable, different OFDM(A) numerologies (e.g., SCSs, CP lengths,and so on) may be configured for a plurality of cells which areaggregated for one UE. Accordingly, the (absolute time) period of a timeresource including the same number of symbols (e.g., a subframe (SF), aslot, or a TTI) (generically referred to as a time unit (TU), forconvenience) may be configured differently for the aggregated cells.

FIG. 7 illustrates an example with μ=2 (i.e., an SCS of 60 kHz), inwhich referring to Table 6, one subframe may include four slots. Onesubframe={1, 2, 4} slots in FIG. 7 , which is exemplary, and the numberof slot(s) which may be included in one subframe is defined as listed inTable 6 or Table 7.

Further, a mini-slot may include 2, 4 or 7 symbols, fewer symbols than2, or more symbols than 7.

FIG. 8 is a diagram illustrating a slot structure in an NR system towhich various embodiments of the present disclosure are applicable.

Referring FIG. 8 , one slot includes a plurality of symbols in the timedomain. For example, one slot includes 7 symbols in a normal CP case and6 symbols in an extended CP case.

A carrier includes a plurality of subcarriers in the frequency domain.An RB is defined by a plurality of (e.g., 12) consecutive subcarriers inthe frequency domain.

A bandwidth part (BWP), which is defined by a plurality of consecutive(P)RBs in the frequency domain, may correspond to one numerology (e.g.,SCS, CP length, and so on).

A carrier may include up to N (e.g., 5) BWPs. Data communication may beconducted in an activated BWP, and only one BWP may be activated for oneUE. In a resource grid, each element is referred to as an RE, to whichone complex symbol may be mapped.

FIG. 9 is a diagram illustrating a self-contained slot structure towhich various embodiments of the present disclosure are applicable.

The self-contained slot structure may refer to a slot structure in whichall of a DL control channel, DL/UL data, and a UL control channel may beincluded in one slot.

In FIG. 9 , the hatched area (e.g., symbol index=0) indicates a DLcontrol region, and the black area (e.g., symbol index=13) indicates aUL control region. The remaining area (e.g., symbol index=1 to 12) maybe used for DL or UL data transmission.

Based on this structure, a BS and a UE may sequentially perform DLtransmission and UL transmission in one slot. That is, the BS and UE maytransmit and receive not only DL data but also a UL ACK/NACK for the DLdata in one slot. Consequently, this structure may reduce a timerequired until data retransmission when a data transmission erroroccurs, thereby minimizing the latency of a final data transmission.

In this self-contained slot structure, a predetermined length of timegap is required to allow the BS and the UE to switch from transmissionmode to reception mode and vice versa. To this end, in theself-contained slot structure, some OFDM symbols at the time ofswitching from DL to UL may be configured as a guard period (GP).

While the self-contained slot structure has been described above asincluding both of a DL control region and a UL control region, thecontrol regions may selectively be included in the self-contained slotstructure. In other words, the self-contained slot structure accordingto various embodiments of the present disclosure may cover a case ofincluding only the DL control region or the UL control region as well asa case of including both of the DL control region and the UL controlregion, as illustrated in FIG. 12 .

Further, the sequence of the regions included in one slot may varyaccording to embodiments. For example, one slot may include the DLcontrol region, the DL data region, the UL control region, and the ULdata region in this order, or the UL control region, the UL data region,the DL control region, and the DL data region in this order.

A PDCCH may be transmitted in the DL control region, and a PDSCH may betransmitted in the DL data region. A PUCCH may be transmitted in the ULcontrol region, and a PUSCH may be transmitted in the UL data region.

The PDCCH may deliver downlink control information (DCI), for example,DL data scheduling information, UL data scheduling information, and soon. The PUCCH may deliver uplink control information (UCI), for example,an acknowledgement/negative acknowledgement (ACK/NACK) information forDL data, channel state information (CSI), a scheduling request (SR), andso on.

The PDSCH conveys DL data (e.g., DL-shared channel transport block(DL-SCH TB)) and uses a modulation scheme such as quadrature phase shiftkeying (QPSK), 16-ary quadrature amplitude modulation (16QAM), 64QAM, or256QAM. A TB is encoded into a codeword. The PDSCH may deliver up to twocodewords. Scrambling and modulation mapping are performed on a codewordbasis, and modulation symbols generated from each codeword are mapped toone or more layers (layer mapping). Each layer together with ademodulation reference signal (DM-RS) is mapped to resources, generatedas an OFDM symbol signal, and transmitted through a correspondingantenna port.

The PDCCH carries downlink control information (DCI) and is modulated inquadrature phase shift keying (QPSK). One PDCCH includes 1, 2, 4, 8, or16 control channel elements (CCEs) according to an aggregation level(AL). One CCE includes 6 resource element groups (REGs). One REG isdefined by one OFDM symbol by one (P)RB.

FIG. 10 is a diagram illustrating the structure of one REG to whichvarious embodiments of the present disclosure are applicable.

In FIG. 10 , D represents an RE to which DCI is mapped, and R representsan RE to which a DM-RS is mapped. The DM-RS is mapped to REs #1, #5, and#9 along the frequency axis in one symbol

The PDCCH is transmitted in a control resource set (CORESET). A CORESETis defined as a set of REGs having a given numerology (e.g., SCS, CPlength, and so on). A plurality of CORESETs for one UE may overlap witheach other in the time/frequency domain. A CORESET may be configured bysystem information (e.g., a master information block (MIB)) or byUE-specific higher layer (RRC) signaling. Specifically, the number ofRBs and the number of symbols (up to 3 symbols) included in a CORESETmay be configured by higher-layer signaling.

The PUSCH delivers UL data (e.g., a UL-shared channel transport block(UL-SCH TB)) and/or UCI, in cyclic prefix-orthogonal frequency divisionmultiplexing (CP-OFDM) waveforms or discrete Fouriertransform-spread-orthogonal division multiplexing (DFT-s-OFDM)waveforms. If the PUSCH is transmitted in DFT-s-OFDM waveforms, the UEtransmits the PUSCH by applying transform precoding. For example, iftransform precoding is impossible (e.g., transform precoding isdisabled), the UE may transmit the PUSCH in CP-OFDM waveforms, and iftransform precoding is possible (e.g., transform precoding is enabled),the UE may transmit the PUSCH in CP-OFDM waveforms or DFT-s-OFDMwaveforms. The PUSCH transmission may be scheduled dynamically by a ULgrant in DCI or semi-statically by higher-layer signaling (e.g., RRCsignaling) (and/or layer 1 (L1) signaling (e.g., a PDCCH)) (a configuredgrant). The PUSCH transmission may be performed in a codebook-based ornon-codebook-based manner.

The PUCCH delivers UCI, an HARQ-ACK, and/or an SR and is classified as ashort PUCCH or a long PUCCH according to the transmission duration ofthe PUCCH. Table 8 lists exemplary PUCCH formats.

TABLE 8 Length in PUCCH OFDM symbols Number format N_(symb) ^(PUCCH) ofbits Usage Etc 0 1-2 ≤2 HARQ, SR Sequence selection 1  4-14 ≤2 HARQ,[SR] Sequence modulation 2 1-2 >2 HARQ, CSI, CP-OFDM [SR] 3  4-14 >2HARQ, CSI, DFT-s-OFDM [SR] (no IE multiplexing) 4  4-14 >2 HARQ, CSI,DFT-s-OFDM [SR] (Pre DFT OCC)

PUCCH format 0 conveys UCI of up to 2 bits and is mapped in asequence-based manner, for transmission. Specifically, the UE transmitsspecific UCI to the BS by transmitting one of a plurality of sequenceson a PUCCH of PUCCH format 0. Only when the UE transmits a positive SR,the UE transmits the PUCCH of PUCCH format 0 in a PUCCH resource for acorresponding SR configuration.

PUCCH format 1 conveys UCI of up to 2 bits and modulation symbols of theUCI are spread with an OCC (which is configured differently whetherfrequency hopping is performed) in the time domain. The DM-RS istransmitted in a symbol in which a modulation symbol is not transmitted(i.e., transmitted in time division multiplexing (TDM)).

PUCCH format 2 conveys UCI of more than 2 bits and modulation symbols ofthe DCI are transmitted in frequency division multiplexing (FDM) withthe DM-RS. The DM-RS is located in symbols #1, #4, #7, and #10 of agiven RB with a density of ⅓. A pseudo noise (PN) sequence is used for aDM-RS sequence. For 1-symbol PUCCH format 2, frequency hopping may beactivated.

PUCCH format 3 does not support UE multiplexing in the same PRBS, andconveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 do not include an OCC. Modulation symbols are transmittedin TDM with the DM-RS.

PUCCH format 4 supports multiplexing of up to 4 UEs in the same PRBS,and conveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 includes an OCC. Modulation symbols are transmitted inTDM with the DM-RS.

1.3. Analog Beamforming

In a millimeter wave (mmW) system, since a wavelength is short, aplurality of antenna elements can be installed in the same area. Thatis, considering that the wavelength at 30 GHz band is 1 cm, a total of100 antenna elements can be installed in a 5*5 cm panel at intervals of0.5 lambda (wavelength) in the case of a 2-dimensional array. Therefore,in the mmW system, it is possible to improve the coverage or throughputby increasing the beamforming (BF) gain using multiple antenna elements.

In this case, each antenna element can include a transceiver unit (TXRU)to enable adjustment of transmit power and phase per antenna element. Bydoing so, each antenna element can perform independent beamforming perfrequency resource.

However, installing TXRUs in all of the about 100 antenna elements isless feasible in terms of cost. Therefore, a method of mapping aplurality of antenna elements to one TXRU and adjusting the direction ofa beam using an analog phase shifter has been considered. However, thismethod is disadvantageous in that frequency selective beamforming isimpossible because only one beam direction is generated over the fullband.

To solve this problem, as an intermediate form of digital BF and analogBF, hybrid BF with B TXRUs that are fewer than Q antenna elements can beconsidered. In the case of the hybrid BF, the number of beam directionsthat can be transmitted at the same time is limited to B or less, whichdepends on how B TXRUs and Q antenna elements are connected.

FIGS. 11 and 12 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements according to various embodiments ofthe present disclosure. Here, the TXRU virtualization model representsthe relationship between TXRU output signals and antenna element outputsignals.

FIG. 11 shows a method for connecting TXRUs to sub-arrays. In FIG. 11 ,one antenna element is connected to one TXRU according to variousembodiments of the present disclosure.

Meanwhile, FIG. 12 shows a method for connecting all TXRUs to allantenna elements. In FIG. 12 , all antenna elements are connected to allTXRUs. In this case, separate addition units are required to connect allantenna elements to all TXRUs as shown in FIG. 12 .

In FIGS. 11 and 12 , W indicates a phase vector weighted by an analogphase shifter. That is, W is a major parameter determining the directionof the analog beamforming. In this case, the mapping relationshipbetween CSI-RS antenna ports and TXRUs may be 1:1 or 1-to-many.

The configuration shown in FIG. 11 has a disadvantage in that it isdifficult to achieve beamforming focusing but has an advantage in thatall antennas can be configured at low cost.

On the contrary, the configuration shown in FIG. 12 is advantageous inthat beamforming focusing can be easily achieved. However, since allantenna elements are connected to the TXRU, it has a disadvantage ofhigh cost.

When a plurality of antennas is used in the NR system to which thepresent disclosure is applicable, a hybrid beamforming (BF) scheme inwhich digital BF and analog BF are combined may be applied. In thiscase, analog BF (or radio frequency (RF) BF) means an operation ofperforming precoding (or combining) at an RF stage. In hybrid BF, eachof a baseband stage and the RF stage perform precoding (or combining)and, therefore, performance approximating to digital BF can be achievedwhile reducing the number of RF chains and the number of adigital-to-analog (D/A) (or analog-to-digital (A/D) converters.

For convenience of description, a hybrid BF structure may be representedby N transceiver units (TXRUs) and M physical antennas. In this case,digital BF for L data layers to be transmitted by a transmission end maybe represented by an N-by-L matrix. N converted digital signals obtainedthereafter are converted into analog signals via the TXRUs and thensubjected to analog BF, which is represented by an M-by-N matrix.

FIG. 13 is a diagram schematically illustrating an exemplary hybrid BFstructure from the perspective of TXRUs and physical antennas accordingto the present disclosure. In FIG. 13 , the number of digital beams is Land the number analog beams is N.

Additionally, in the NR system to which the present disclosure isapplicable, an BS designs analog BF to be changed in units of symbols toprovide more efficient BF support to a UE located in a specific area.Furthermore, as illustrated in FIG. 13 , when N specific TXRUs and M RFantennas are defined as one antenna panel, the NR system according tothe present disclosure considers introducing a plurality of antennapanels to which independent hybrid BF is applicable.

In the case in which the BS utilizes a plurality of analog beams asdescribed above, the analog beams advantageous for signal reception maydiffer according to a UE. Therefore, in the NR system to which thepresent disclosure is applicable, a beam sweeping operation is beingconsidered in which the BS transmits signals (at least synchronizationsignals, system information, paging, and the like) by applying differentanalog beams in a specific subframe (SF) or slot on a symbol-by-symbolbasis so that all UEs may have reception opportunities.

FIG. 14 is a diagram schematically illustrating an exemplary beamsweeping operation for a synchronization signal and system informationin a DL transmission procedure according to various embodiments of thepresent disclosure.

In FIG. 14 below, a physical resource (or physical channel) on which thesystem information of the NR system to which the present disclosure isapplicable is transmitted in a broadcasting manner is referred to as anxPBCH. Here, analog beams belonging to different antenna panels withinone symbol may be simultaneously transmitted.

As illustrated in FIG. 14 , in order to measure a channel for eachanalog beam in the NR system to which the present disclosure isapplicable, introducing a beam RS (BRS), which is a reference signal(RS) transmitted by applying a single analog beam (corresponding to aspecific antenna panel), is being discussed. The BRS may be defined fora plurality of antenna ports and each antenna port of the BRS maycorrespond to a single analog beam. In this case, unlike the BRS, asynchronization signal or the xPBCH may be transmitted by applying allanalog beams in an analog beam group such that any UE may receive thesignal well.

1.4. Synchronization Signal Block (SSB) or SS/PBCH Block

In the NR system to which the present disclosure is applicable, aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and/or a physical broadcast signal (PBCH) may be transmitted inone SS block or SS PBCH block (hereinafter, referred to as an SSB orSS/PBCH block). Multiplexing other signals may not be precluded withinthe SSB.

The SS/PBCH block may be transmitted in a band other than the center ofa system band. Particularly, when the BS supports broadband operation,the BS may transmit multiple SS/PBCH blocks.

FIG. 15 is a schematic diagram illustrating an SS/PBCH block applicableto the present disclosure.

As illustrated in FIG. 15 , the SS/PBCH block applicable to the presentdisclosure may include 20 RBs in four consecutive OFDM symbols. Further,the SS/PBCH block may include a PSS, an SSS, and a PBCH, and the UE mayperform cell search, system information acquisition, beam alignment forinitial access, DL measurement, and so on based on the SS/PBCH block.

Each of the PSS and the SSS includes one OFDM symbol by 127 subcarriers,and the PBCH includes three OFDM symbols by 576 subcarriers. Polarcoding and QPSK are applied to the PBCH. The PBCH includes data REs andDM-RS REs in every OFDM symbol. There are three DM-RS REs per RB, withthree data REs between every two adjacent DM-RS REs.

Further, the SS/PBCH block may be transmitted even in a frequency bandother than the center frequency of a frequency band used by the network.

For this purpose, a synchronization raster being candidate frequencypositions at which the UE should detect the SS/PBCH block is defined inthe NR system to which the present disclosure is applicable. Thesynchronization raster may be distinguished from a channel raster.

In the absence of explicit signaling of the position of the SS/PBCHblock, the synchronization raster may indicate available frequencypositions for the SS/PBCH block, at which the UE may acquire systeminformation.

The synchronization raster may be determined based on a globalsynchronization channel number (GSCN). The GSCN may be transmitted byRRC signaling (e.g., an MIB, a system information block (SIB), remainingminimum system information (RMSI), other system information (OSI), orthe like).

The synchronization raster is defined to be longer along the frequencyaxis than the channel raster and characterized by a smaller number ofblind detections than the channel raster, in consideration of thecomplexity of initial synchronization and a detection speed.

FIG. 16 is a schematic diagram illustrating an SS/PBCH blocktransmission structure applicable to the present disclosure.

In the NR system to which the present disclosure is applicable, the BSmay transmit an SS/PBCH block up to 64 times for 5 ms. The multipleSS/PBCH blocks may be transmitted on different beams, and the UE maydetect the SS/PBCH block on the assumption that the SS/PBCH block istransmitted on a specific one beam every 20 ms.

As the frequency band is higher, the BS may set a larger maximum numberof beams available for SS/PBCH block transmission within 5 ms. Forexample, the BS may transmit the SS/PBCH block by using up to 4different beams at or below 3 GHz, up to 8 different beams at 3 to 6GHz, and up to 64 different beams at or above 6 GHz, for 5 ms.

1.5. Synchronization Procedure

The UE may acquire synchronization by receiving the above-describedSS/PBCH block from the BS. The synchronization procedure largelyincludes cell ID detection and timing detection. The cell ID detectionmay include PSS-based cell ID detection and SSS-based cell ID detection.The timing detection may include PBCH DM-RS-based timing detection andPBCH contents-based (e.g., MIB-based) timing detection.

First, the UE may acquire timing synchronization and the physical cellID of a detected cell by detecting a PSS and an SSS. More specifically,the UE may acquire the symbol timing of the SS block and detect a cellID within a cell ID group, by PSS detection. Subsequently, the UEdetects the cell ID group by SSS detection.

Further, the UE may detect the time index (e.g., slot boundary) of theSS block by the DM-RS of the PBCH. The UE may then acquire half-frameboundary information and system frame number (SFN) information from anMIB included in the PBCH.

The PBCH may indicate that a related (or corresponding) RMSI PDCCH/PDSCHis transmitted in the same band as or a different band from that of theSS/PBCH block. Accordingly, the UE may then receive RMSI (e.g., systeminformation other than the MIB) in a frequency band indicated by thePBCH or a frequency band carrying the PBCH, after decoding of the PBCH.

In relation to the operation, the UE may acquire system information.

The MIB includes information/parameters required for monitoring a PDCCHthat schedules a PDSCH carrying SystemInformationBlock1 (SIB1), and istransmitted to the UE on the PBCH in the SS/PBCH block by the gNB.

The UE may check whether there is a CORESET for a Type0-PDCCH commonsearch space, based on the MIB. The Type0-PDCCH common search space is akind of PDCCH search space and used to transmit a PDCCH that schedulesan SI message.

In the presence of a Type0-PDCCH common search space, the UE maydetermine (i) a plurality of contiguous RBs included in the CORESET andone or more consecutive symbols and (ii) a PDCCH occasion (e.g., atime-domain position for PDCCH reception), based on information (e.g.,pdcch-ConfigSIB1) included in the MIB.

In the absence of a Type0-PDCCH common search space, pdcch-ConfigSIB1provides information about a frequency position at which the SSB/SIB1exists and a frequency range in which the SSB/SIB1 does not exist.

SIB1 includes information about the availability and scheduling of theother SIBs (hereinafter, referred to as SIBx where x is 2 or a largerinteger). For example, SIB1 may indicate whether SIBx is periodicallybroadcast or provided in an on-demand manner (or upon request of theUE). When SIBx is provided in the on-demand manner, SIB1 may includeinformation required for an SI request of the UE. SIB1 is transmitted ona PDSCH. A PDCCH that schedules SIB1 is transmitted in a Type0-PDCCHcommon search space, and SIB1 is transmitted on a PDSCH indicated by thePDCCH.

1.6. Quasi Co-Located or Quasi Co-Location (QCL)

In the present disclosure, QCL may mean one of the following.

(1) If two antenna ports are “quasi co-located (QCL)”, the UE may assumethat large-scale properties of a signal received from a first antennaport may be inferred from a signal received from the other antenna port.The “large-scale properties” may include one or more of the following.

-   -   Delay spread    -   Doppler spread    -   Frequency shift    -   Average received power    -   Received Timing

(2) If two antenna ports are “quasi co-located (QCL)”, the UE may assumethat large-scale properties of a channel over which a symbol on oneantenna port is conveyed may be inferred from a channel over which asymbol on the other antenna port is conveyed). The “large-scaleproperties” may include one or more of the following.

-   -   Delay spread    -   Doppler spread    -   Doppler shift    -   Average gain    -   Average delay    -   Average angle (AA): When it is said that QCL is guaranteed        between antenna ports in terms of AA, this may imply that when a        signal is to be received from other antenna port(s) based on an        AA estimated from specific antenna port(s), the same or similar        reception beam direction (and/or reception beam width/sweeping        degree) may be set and the reception is processed accordingly        (in other words, that when operated in this manner, reception        performance at or above a certain level is guaranteed).    -   Angular spread (AS): When it is said that QCL is guaranteed        between antenna ports in terms of AS, this may imply that an AS        estimated from one antenna port may be derived/estimated/applied        from an AS estimated from another antenna port.    -   Power Angle(-of-Arrival) Profile (PAP): When it is said that QCL        is guaranteed between antenna ports in terms of PAP, this may        imply that a PAP estimated from one antenna port may be        derived/estimated/applied from a PAP estimated from another        antenna port (or the PAPs may be treated as similar or        identical).

In the present disclosure, both of the concepts defined in (1) and (2)described above may be applied to QCL. Alternatively, the QCL conceptsmay be modified such that it may be assumed that signals are transmittedfrom a co-location, for signal transmission from antenna ports for whichthe QCL assumption is established (e.g., the UE may assume that theantenna ports are transmitted from the same transmission point).

In the present disclosure, partial QCL between two antenna ports maymean that at least one of the foregoing QCL parameters for one antennaport is assumed/applied/used as the same as for the other antenna port(when an associated operation is applied, performance at or above acertain level is guaranteed).

1.7. Bandwidth Part (BWP)

In the NR system to which the present disclosure is applicable,frequency resources of up to 400 MHz per component carrier (CC) may beallocated/supported. When a UE operating in such a wideband CC alwaysoperates with a radio frequency (RF) module for the entire CCs turnedon, battery consumption of the UE may increase.

Alternatively, considering various use cases (e.g., enhanced mobilebroadband (eMBB), ultra-reliable and low latency communication (URLLC),and massive machine type communication (mMTC), and so on) operatingwithin a single wideband CC, a different numerology (e.g., SCS) may besupported for each frequency band within the CC.

Alternatively, the maximum bandwidth capability may be different foreach UE.

In consideration of the above situation, the BS may indicate/configurethe UE to operate only in a partial bandwidth instead of the entirebandwidth of the wideband CC. The partial bandwidth may be defined as aBWP.

A BWP may include contiguous RBs on the frequency axis, and one BWP maycorrespond to one numerology (e.g., SCS, CP length, slot/mini-slotduration, and so on).

The BS may configure a plurality of BWPs in one CC configured for theUE. For example, the BS may configure a BWP occupying a relatively smallfrequency area in a PDCCH monitoring slot, and schedule a PDSCHindicated by the PDCCH (or a PDSCH scheduled by the PDCCH) in a largerBWP. Alternatively, when UEs are concentrated on a specific BWP, the BSmay configure another BWP for some of the UEs, for load balancing.Alternatively, the BS may exclude some spectrum of the entire bandwidthand configure both of the BWPs in the same slot in consideration offrequency-domain inter-cell interference cancellation betweenneighboring cells.

The BS may configure at least one DL/UL BWP for a UE associated with awideband CC, activate at least one of the configured DL/UL BWP(s) at aspecific time (by L1 signaling (e.g., DCI or the like), MAC signaling,or RRC signaling). The activated DL/UL BWP may be referred to as anactive DL/UL BWP. Before initial access or RRC connection setup, the UEmay not receive a DL/UL BWP configuration from the BS. A DL/UL BWP thatthe UE assumes in this situation is defined as an initial active DL/ULBWP.

More specifically, according to various embodiments of the presentdisclosure, the UE may perform the following BWP operation.

A UE, which has been configured to operate BWPs of a serving cell, isconfigured with up to four DL BWPs within the DL bandwidth of theserving cell by a higher-layer parameter (e.g., DL-BWP or BWP-Downlink)and up to four UL BWPs within the UL bandwidth of the serving cell by ahigher-layer parameter (e.g., UL-BWP or BWP-Uplink).

When the UE fails to receive a higher-layer parameterinitialDownlinkBWP, an initial active DL BWP may be defined by thepositions and number of consecutive PRBs: consecutive PRBs from thelowest index to the highest index among PRBs included in a CORESET for aType-0 PDCCH CSS set. Further, the initial active DL BWP is defined byan SCS and a CP for PDCCH reception in the CORESET for the Type-0 PDCCHCSS set. Alternatively, the initial active DL BWP is provided by thehigher-layer parameter initialDownlinkBWP. For an operation in a primarycell or a secondary cell, an initial active UL BWP is indicated to theUE by a higher-layer parameter initialUplinkBWP. When a supplementary ULcarrier is configured for the UE, an initial active UL BWP on thesupplementary UL carrier may be indicated to the UE by initialUplinkBWin a higher-layer parameter supplementaryUplink.

When the UE has a dedicated BWP configuration, the UE may be providedwith a first active DL BWP for reception by a higher-layerparameterfirstActiveDownlinkBWP-Id and a first active UL BWP fortransmission on the carrier of the primary cell by a higher-layerparameter firstActiveUplinkGBWP-Id.

For each DL BWP of a DL BWP set or each UL BWP of a UL BWP set, the UEmay be provided with the following parameters.

-   -   An SCS provided based on a higher-layer parameter (e.g.,        subcarrierSpacing).    -   A CP provided based on a higher-layer parameter (e.g.,        cyclicPrefix).    -   The number of common RBs and contiguous RBs is provided based on        a higher-layer parameter locationAndBandwidth. The higher-layer        parameter locationAndBandwidth indicates an offset RB_(start)        and a length L_(RB) based on a resource indication value (RIV).        It is assumed that N^(size) _(BWP) is 275 and O_(carrier) is        provided by offsetToCarrier for the higher-layer parameter        subcarrierSpacing.    -   An index in the set of DL BWPs or the set of UL BWPs, provided        based on a higher-layer parameter (e.g., bwp-Id) in UL and DL        independently.    -   A BWP-common set parameter or BWP-dedicated set parameter        provided based on a higher-layer parameter (e.g., bwp-Common or        bwp-Dedicated).

For an unpaired spectrum operation, a DL BWP in a set of DL BWPs withindexes provided by a higher-layer parameter (e.g., bwp-/d) is linked toa UL BWP in a set of UL BWPs with the same indexes, when the DL BWPindex and the UL BWP index are identical. For the unpaired spectrumoperation, when the higher-layer parameter b p-Id of a DL BWP is thesame as the higher-layer parameter bvp-Id of a UL BWP, the UE does notexpect to receive a configuration in which the center frequency for theDL BWP is different from the center frequency for the UL BWP.

For each DL BWP in a set of DL BWPs of the primary cell (referred to asPCell) or of a PUCCH secondary cell (referred to as PUCCH-SCell), the UEmay configure CORESETs for every CSS set and a USS. The UE does notexpect to be configured without a CSS on the PCell or the PUCCH-SCell inan active DL BWP.

When the UE is provided with controlResourceSetZero and searchSpaceZeroin a higher-layer parameter PDCCH-ConfigSIB1 or a higher-layer parameterPDCCH-ConfigCommon, the UE determines a CORESET for a search space setbased on controlResourceseiZero and determines corresponding PDCCHmonitoring occasions. When the active DL BWP is not the initial DL BWP,the UE determines PDCCH monitoring occasions for the search space set,only if the bandwidth of the CORESET is within the active DL BWP and theactive DL BWP has the same SCS configuration and CP as the initial DLBWP.

For each UL BWP in a set of UL BWPs of the PCell or the PUCCH-SCell, theUE is configured with resource sets for PUCCH transmissions.

The UE receives a PDCCH and a PDSCH in a DL BWP according to aconfigured SCS and CP length for the DL BWP. The UE transmits a PUCCHand a PUSCH in a UL BWP according to a configured SCS and CP length forthe UL BWP.

When a bandwidth part indicator field is configured in DCI format 1_1,the value of the bandwidth part indicator field indicates an active DLBWP in the configured DL BWP set, for DL receptions. When a bandwidthpart indicator field is configured in DCI format 0_1, the value of thebandwidth part indicator field indicates an active UL BWP in theconfigured UL BWP set, for UL transmissions.

If a bandwidth part indicator field is configured in DCI format 0_1 orDCI format 1_1 and indicates a UL or DL BWP different from the active ULBWP or DL BWP, respectively, the IE may operate as follows.

-   -   For each information field in the received DCI format 0_1 or DCI        format 1_1,        -   if the size of the information field is smaller than a size            required for interpretation of DCI format 0_1 or DCI format            1_1 for the UL BWP or DL BWP indicated by the bandwidth part            indicator, the UE prepends zeros to the information field            until its size is the size required for the interpretation            of the information field for the UL BWP or DL BWP before the            information field of DCI format 0_1 or DCII format 1_1 is            interpreted.        -   if the size of the information field is larger than the size            required for interpretation of DCI format 0_1 or DCI format            1_1 for the UL BWP or DL BWP indicated by the bandwidth part            indicator, the UE uses as many least significant bits (LSBs)            of DCI format 0_1 or DCI format 1_1 as the size required for            the UL BWP or DL BWP indicated by the bandwidth part            indicator before interpreting the information field of DCI            format 0_1 or DCI format 1_1.    -   The UE sets the active UL BWP or DL BWP to the UL BWP or DL B P        indicated by the bandwidth part indicator in DCI format 0_1 or        DCI format 1_1.

The UE does not expect to detect DCI format 1_1 or DCI format 0_1indicating an active DL BWP or active UL BWP change with a time-domainresource assignment field providing a slot offset value smaller than adelay required for the UE for an active DL BWP change or UL BWP change.

When the UE detects DCI format 1_1 indicating an active DL BWP changefor a cell, the UE is not required to receive or transmit a signal inthe cell during a time period from the end of the third symbol of a slotin which the UE receives a PDCCH including DCI format 1_1 until thebeginning of a slot indicated by the slot offset value of thetime-domain resource assignment field in DC format 1_1.

If the LE detects DCI format 0_1 indicating an active UL BWP change fora cell, the UE is not required to receive or transmit a signal in thecell during a time period from the end of the third symbol of a slot inwhich the UE receives a PDCCH including DCI format 0_1 until thebeginning of a slot indicated by the slot offset value of thetime-domain resource assignment field in DCI format 0_1.

The UE does not expect to detect DCI format 1_1 indicating an active DLBWP change or DCI format 0_1 indicating an active UL BWP change in aslot other than the first slot of a set of slots for the SCS of a cellthat overlaps with a time period during which the UE is not required toreceive or transmit a signal for an active BWP change in a differentcell.

The UE expects to detect DCI format 0_1 indicating an active UL BWPchange or DCI format 1_1 indicating an active DL BWP change, only if acorresponding PDCCH is received within the first 3 symbols of a slot.

For the serving cell, the UE may be provided with a higher-layerparameter defaultDownlinkBVP-Id indicating a default DL BWP among theconfigured DL BWPs. If the UE is not provided with a default DL BWP bydefaultDownlinkBWP-Id, the default DL BWP may be set to the initialactive DL BWP.

When the UE is provided with a timer value for the PCell by ahigher-layer parameter bwp-Inactivity Timer and the timer is running,the UE decrements the timer at the end of a subframe for FR1 (below 6GHz) or at the end of a half subframe for FR2 (above 6 GHz), if arestarting condition is not met during a time period corresponding tothe subframe for FR1 or a time period corresponding to the half-subframefor FR2.

For a cell in which the UE changes an active DL BWP due to expiration ofa BWP inactivity timer and for accommodating a delay in the active DLBWP change or the active UL BWP change required by the UE, the UE is notrequired to receive or transmit a signal in the cell during a timeperiod from the beginning of a subframe for FR1 or a half subframe forFR2, immediately after the BWP inactivity timer expires until thebeginning of a slot in which the UT may receive or transmit a signal.

When the BWP inactivity timer of the UE for the specific cell expireswithin the time period during which the UE is not required to receive ortransmit a signal for the active UL/DL BWP change in the cell or in adifferent cell, the UE may delay the active UL/DL BWP change triggeredby expiration of the BWP activity timer until the subframe for FR1 orthe half-subframe for FR2 immediately after the UE completes the activeUL/DL BWP change in the cell or in the different cell.

When the UE is provided with a first active DL BWP by a higher-layerparameter firstActiveDownlinkBWP-Id and a first active UL BWP by ahigher-layer parameter firstActiveUplinkBWP-ID on a carrier of thesecondary cell, the UE uses the indicated DL BWP and the indicated ULBWP as the respective first active DL BWP and first active UL BWP on thecarrier of the secondary cell.

For a paired spectrum operation, when the UE changes an active UL BWP onthe PCell during a time period between a detection time of DCI format1-0 or DC format 1_1 and a transmission time of a corresponding PUCCHincluding HARQ-ACK information, the UE does not expect to transmit thePUCCH including the HARQ-ACK information in PUCCH resources indicated byDCI format 1_0 or DCI format 1_1.

When the UE performs radio resource management (RRM) measurement for abandwidth outside the active DL BWP for the UE, the UE does not expectto monitor a PDCCH.

1.8. Slot Configuration

In various embodiments of the present disclosure, a slot format includesone or more DL symbols, one or more UL symbols, and a flexible symbol.In various embodiments of the present disclosure, the correspondingconfigurations will be described as DL, UL, and flexible symbol(s),respectively, for the convenience of description.

The following may be applied to each serving cell.

When the UE is provided with a higher-layer parameterTDD-UL-DL-ConfigurationCommon, the UE may configure a slot format perslot over a certain number of slots, indicated by the higher-layerparameter TDD-UL-DL-ConfigurationCommon.

The higher-layer parameter TDD-UL-DL-ConfigurationCommon may provide thefollowing.

-   -   A reference SCS configuration μ_(ref) based on a higher-layer        parameter referenceSubcarrierSpacing.    -   A higher-layer parameter pattern1.

The higher-layer parameter pattern1 may provide the following.

-   -   A slot configuration periodicity P msec based on a higher-layer        parameter dl-UL-TransmissionPeriodicity.    -   The number d_(slots) of slots including only DL symbols based on        a higher-layer parameter nrofDownlinkSlots.    -   The number d_(symb) of DL symbols based on a higher-layer        parameter nrofDownlinkSymbols.    -   The number μ_(slots) of slots including only UL symbols based on        a higher-layer parameter nrofUplinkSlots.    -   The number U_(sym) of UL symbols based on a higher-layer        parameter nrofUplinkSymbols.

For an SCS configuration μ_(ref)=3, only P=0.625 msec may be valid. Foran SCS configuration μ_(ref)=2 or μ_(ref)=3, only P=1.25 msec may bevalid. For an SCS configuration μ_(ref)=1, μ_(ref)=2 or μ_(ref)=³, onlyP=2.5 msec may be valid.

The slot configuration periodicity (P msec) includes S slots given byS=P·2^(μ) ^(ref) in an SCS configuration μ_(ref). The first d_(slots)slots of the S slots include only DL symbols, and the last u_(slots)slots of the S slots include only UL symbols. d_(sym) symbols followingthe first d_(slots) slots are DL symbols. u_(sym) symbols preceding theu_(slots) slots are UL symbols. The remaining(S−d_(slots)−u_(slots))·N_(symb) ^(slot)−d_(sym)−u_(sym) symbols areflexible symbols.

The first symbol of every 20/P period is the first symbol of aneven-numbered frame.

When the higher-layer parameter TDD-UL-DL-ConfigurationCommon provideshigher-layer parameters pattern1 and pattern2, the UE configures a slotformat per slot over a first number of slots based on the higher-layerparameter pattern1, and a slot format per slot over a second number ofslots based on the higher-layer parameter pattern2.

The higher-layer parameter pattern2 may provide the following.

-   -   A slot configuration periodicity P₂ msec based on a higher-layer        parameter dl-UL-TransmissionPeriodicity.    -   The number d_(slots,2) of slots including only DL symbols based        on a higher-layer parameter nrofDownlinkSlots.    -   The number d_(sym,2) of DL symbols based on a higher-layer        parameter nrofDownlinkSymbols.    -   The number u_(slots,2) of slots including only UL symbols based        on a higher-layer parameter nrofUplinkSlots.    -   The number u_(sym,2) of UL symbols based on a higher-layer        parameter nrofUplinkSymbols.

A P₂ value applicable according to an SCS configuration is equal to a Pvalue applicable according to the SCS configuration.

A slot configuration periodicity P+P2 msec includes the first S slotswhere S=P·2^(μ) ^(ref) and the second S₂ slots where S₂=P₂·2^(μ) ^(ref).

The first d_(slots,2) ones of the S₂ slots include only DL symbols, andthe last u_(slots,2) ones of the S₂ slots include only UL symbols.d_(sym,2) symbols following the first d_(slots,2) slots are DL symbols.u_(sym,2) symbols preceding the u_(slots,2) slots are UL symbols. Theremaining (S₂−d_(slots,2)−u_(slots))·N_(symb)^(slot)−d_(sym,2)−u_(sym,2) symbols are flexible symbols.

The UE expects the value of P+P₂ to be divided by 20 msec without aremainder. In other words, the UE expects the value of P+P2 to be aninteger multiple of 20 msec.

The first symbol of every 20/(P+P₂) period is the first symbol of aneven-numbered frame.

The UE expects that the reference SCS configuration μ_(ref) is smallerthan or equal to an SCS configuration μ for any configured DL BWP or ULBWP. Each slot (configuration) provided by the higher-layer parameterpattern1 or pattern2 is applicable to 2^((μ-μ) ^(ref) ⁾ consecutiveslots in the active DL BWP or active UL BWP in the first slot whichstarts at the same time as the first slot for the reference SCSconfiguration μ_(ref). Each DL, flexible, or UL symbol for the referenceSCS configuration μ_(ref) corresponds to 2^((μ-μ) ^(ref) ⁾, consecutiveDL, flexible, or UL symbols for the SCS configuration μ.

When the UE is additionally provided with a higher-layer parameterTdd-UL-DL-ConfigurationDedicatec, the higher-layer parameterTdcdUL-DL-ConfigurationDedicated overrides only flexible symbols perslot over the number of slots as provided by the higher-layer parameterTdd-UL-DL-ConfIgurationCommon.

The higher-layer parameter Tdd-UL-DL-ConfigurationDedicated may providethe following.

-   -   A set of slot configurations based on a higher-layer parameter        slotSpecificConiguractionsToAddModList.    -   Each slot configuration in the set of slot configurations.    -   A slot index based on a higher-layer parameter slotIndex.    -   A set of symbols based on a higher-layer parameter symbols.        -   If the higher-layer parameter symbols=allDownlink, all            symbols in the slot are DL symbols.        -   If the higher-layer parameter symbols=allUplink, all symbols            in the slot are UL symbols.        -   If the higher-layer parameter symbols=explicit, the            higher-layer parameter nrofDowniinkSymbols provides the            number of first DL symbols in the slot, and the higher-layer            parameter nrofUplinkSymbols provides the number of last UL            symbols in the slot. If the higher-layer parameter            nrofDownlinkSymbols is not provided, this implies that there            are no first DL symbols in the slot. If the higher-layer            parameter nrofUplinkSymbols is not provided, this implies            that there are no last UL symbols in the slot. The remaining            symbols in the slot are flexible symbols.

For each slot having an index provided by a higher-layer parameterslotIndex, the UE applies a (slot) format provided by a correspondingsymbols. The UE does not expect the higher-layer parameterTDD-UL-DL-ConfigurationDedicated to indicate, as UT or DL, a symbol thatthe higher-layer parameter TDD-L-DL-ConfigurationCommon indicates as DLor UL.

For each slot configuration provided by the higher-layer parameterTDD-UL-DL-ConfigurationDedicated, a reference SCS configuration is thereference SCS configuration μ_(ref) provided by the higher-layerparameter TDD-UL-DL-ConfigurationCommon.

A slot configuration periodicity and the number of DL/UL/flexiblesymbols in each slot of the slot configuration periodicity is determinedbased on the higher-layer parameters TDD-UL-DL-ConfigurationCommon andTDD-UL-DL-ConfigurationDedicated, and the information is common to eachconfigured BWP

The UE considers symbols in a slot indicated as DL by the higher-layerparameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated to be available for signal reception.Further, the UE considers symbols in a slot indicated as UL by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated to be available for signaltransmission.

If the UE is not configured to monitor a PDCCH for DCI format 2_0, for aset of symbols of a slot that are indicated as flexible by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated, or when the higher-layer parametersTDD-UL-DL-ConfigurationCommon and TDD-UL-DL-ConfigurationDedicated arenot provided to the UE, the UE may operate as follows.

-   -   The UE may receive a PDSCH or a CSI-RS in the set of symbols of        the slot, when the UE receives a corresponding indication by DCI        format 1_0, DCI format 1_1, or DCI format 0_1.    -   The UE may transmit a PUSCH, a PUCCH, a PRACH, or an SRS in the        set of symbols of the slot, if the UE receives a corresponding        indication by DCI format 0_0, DCI format 0_1, DCI format 1_0,        DCI format 1_1, or DCI format 2_3.

It is assumed that the UE is configured by the higher layer to receive aPDCCH, a PDSCH, or a CSI-RS in a set of symbols of a slot. When the UEdoes not detect DCI format 0_0, DCI format 0_1, DCI format 1_0, DCIformat 1_1, or DCI format 2_3 that indicates to the UE to transmit aPUSCH, a PUCCH, a PRACH, or an SRS in at least one symbol of the set ofsymbols of the slot, the UE may receive the PDCCH, the PDSCH, or theCSI-RS. Otherwise, that is, when the UE detects DCI format 0_0, DCIformat 0_1, DCI format 1_0, DCI format 1_1, or DCI format 2_3 thatindicates to the UE to transmit a PUSCH, a PUCCH, a PRACH, or an SRS inat least one symbol of the set of symbols of the slot, the UE does notreceive the PDCCH, the PDSCH, or the CSI-RS in the set of symbols of theslot.

When the UE is configured by the higher layer to transmit an SRS, aPUCCH, a PUSCH, or a PRACH in a set of symbols of a slot and detects DCIformat 1_0, DCI format 1_1, or DCI format 0_1 indicating to the UE toreceive a CSI-RS or a PDSCH in a subset of symbols from the set ofsymbols, the UE operates as follows.

-   -   The UE does not expect to cancel signal transmission in a subset        of symbols that occur after fewer symbols than a PUSCH        preparation time T_(proc,2) for a corresponding UE processing        capability on the assumption that d_(2,1)=1, relative to the        last symbol of a CORESET in which the UE detects DCI format 1_0,        DCI format 1_1, or DCI format 0_1.    -   The UE cancels the PUCCH, PUSCH, or PRACH transmission in the        remaining symbols of the set of symbols, and cancels the SRS        transmission in the remaining symbols of the set of symbols.

For a set of symbols of a slot that are indicated as UL by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated, the UE does not receive a PDCCH, aPDSCH, or a CSI-RS in the set of symbols of the slot.

For a set of symbols of a slot that are indicated as DL by thehigher-layer parameter DD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated, the UE does not transmit a PUSCH, aPUCCH, a PRACH, or an SRS in the set of symbols of the slot.

For a set of symbols of a slot that are indicated as flexible by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigurationDedicated, the UE does not expect to receive adedicated configuration for transmission from the UE and a dedicatedconfiguration for reception at the UE in the set of symbols of the slot.

For a set of symbols of a slot indicated by a higher-layer parameterssb-PositionsInBurst in a higher-layer parameterSystemInformationBlockType1 or ServingCellConfigCommon, for reception ofSS/PBCH blocks, the UE does not transmit a PUSCH, a PUCCH, or a PRACH inthe slot if a transmission overlaps with any symbol of the set ofsymbols, and the UE does not transmit an SRS in the set of symbols ofthe slot. When the higher-layer parameter TDD-UL-DL-ConfigurationCommonor TDD-UL-DL-ConfigDedicated is provided to the UE, the UE does notexpect the set of symbols of the slot to be indicated as UL by thehigher-layer parameter.

For a set of symbols of a slot corresponding to a valid PRACH occasion,and N_(gap) symbols before the valid PRACH occasion, when a signalreception overlaps with any symbol of the set of symbols in the slot,the UE does not receive a PDCCH, a PDSCH, or a CSI-RS for a Type1-PDCCHCSS set. The UE does not expect the set of symbols of the slot to beindicated as DL by the higher-layer parameterTDD-UL-DL-ConfigurationCommon or TDD-UL-DL-ConfigDedicated.

For a set of symbols of a slot indicated by a higher-layer parameterpdcch-ConfigSIB1 in an MIB for a CORESET for a Type0-PDCCH CSS set, theUE does not expect the set of symbols to be indicated as UL by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon orTDD-UL-DL-ConfigDedicated.

When the UE is scheduled by DCI format 1_1 to receive a PDSCH overmultiple slots, and the higher-layer parameterTDD-UL-DL-ConfigurationCommon or TDD-UL-DL-ConfigDedicated indicatesthat, for one of the multiple slots, at least one symbol in a set ofsymbols in which the UE is scheduled to receive a PDSCH in the slot is aUL symbol, the UE does not receive the PDSCH in the slot.

When the UE is scheduled by DCI format 0_1 to transmit a PUSCH overmultiple slots, and the higher-layer parameterTDD-UL-DL-ConfigurationCommon or TDD-UL-DL-ConfigDedicated indicatesthat, for one of the multiple slots, at least one symbol in a set ofsymbols in which the UE is scheduled to receive a PDSCH in the slot is aDL symbol, the UE does not transmit the PUSCH in the slot.

A detailed description will be given below of a UE operation fordetermining a slot format. The UE operation may apply for a serving cellincluded in a set of serving cells configured for a UE by higher-layerparameters slotFormatCombToAddModList and slotFormatCombToReleaseList.

If the UE is configured with a higher-layer parameterSlotFormatIndicator, the UE is provided with an SFI-RNTI by ahigher-layer parameter sfi-RNTI and with a payload size of DCI format2_0 by a higher-layer parameter dci-PayloadSize.

For one or more serving cells, the UE is also provided with aconfiguration for a search space set S and a corresponding CORESET P.The search space set S and the corresponding CORESET P may be providedfor monitoring M_(p,s) ^((L) ^(SFI) ⁾ PDCCH candidates for DCI format2_0 with a CCE aggregation level including L_(SFI) CCEs.

The M_(p,s) ^((L) ^(SFI) ⁾ PDCCH candidates are the first M_(p,s) ^((L)^(SFI) ⁾ PDCCH candidates for the CCE aggregation level L_(SFI) for thesearch space set S in the CORESET P.

For each serving cell in the set of serving cells, the UE may beprovided with:

-   -   an ID of the serving cell based on a higher-layer parameter        servingCellId.    -   a location of an SFI-index field in DCI format 2_0 based on a        higher-layer parameter positionInDCI.    -   a set of slot format combinations based on a higher-layer        parameter slotFormatCombinations, where each slot format        combination in the set of slot format combinations includes        -   one or more slot formats based on a higher-layer parameter            slotFormats for the slot format combination, and        -   mapping for the slot format combination provided by the            higher-layer parameter slotFormats to a corresponding            SFI-index field value in DCI format 2_0 provided by a            higher-layer parameter slotFormatCombinationId.    -   for an unpaired spectrum operation, a reference SCS        configuration μ_(SFI) based on a higher-layer parameter        subcarrierSpacing. When a supplementary UL carrier is configured        for the serving cell, a reference SCS configuration μ_(SFI,SUL)        based on a higher-layer parameter subcarrierSpacing2 for the        supplementary UL carrier.    -   for a paired spectrum operation, a reference SCS configuration        μSFI,DL for a DL BWP based on the higher-layer parameter        subcarrierSpacing and a reference SCS configuration μ_(SFI,UL)        for an UL BWP based on the higher-layer parameter        subcarrierSpacing2.

An SFI-index field value in DCI format 2_0 indicates to the UE a slotformat for each slot in a number of slots for each DL BWP or each UL BWPstarting from a slot in which the UE detects DCI format 2_0. The numberof slots is equal to or larger than a PDCCH monitoring periodicity forDCI format 2_0. The SFI-index field includes max {┌log₂(maxSFIindex+1)┐,1} bits where maxSFIindex is the maximum of the values provided by thecorresponding higher-layer parameter slotFormatCombinationId. A slotformat is identified by a corresponding format index as provided inTable 11 to Table 14. In Table 9 to Table 12, ‘D’ denotes a DL symbol,‘U’ denotes a UL symbol, and ‘F’ denotes a flexible symbol. In Table 9to Table 12, ‘D’ denotes a DL symbol, ‘U’ denotes a UL symbol, and ‘F’denotes a flexible symbol.

TABLE 9 For- Symbol number in a slot mat 0 1 2 3 4 5 6 7 8 9 10 11 12 130 D D D D D D D D D D D D D D 1 U U U U U U U U U U U U U U 2 F F F F FF F F F F F F F F 3 D D D D D D D D D D D D D F 4 D D D D D D D D D D DD F F 5 D D D D D D D D D D D F F F 6 D D D D D D D D D D F F F F 7 D DD D D D D D D F F F F F 8 F F F F F F F F F F F F U U 9 F F F F F F F FF F F F U U 10 F U U U U U U U U U U U U U 11 F F U U U U U U U U U U UU 12 F F F U U U U U U U U U U U 13 F F F F U U U U U U U U U U 14 F F FF F U U U U U U U U U

TABLE 10 15 F F F F F F U U U U U U U U 16 D F F F F F F F F F F F F F17 D D F F F F F F F F F F F F 18 D D D F F F F F F F F F F F 19 D F F FF F F F F F F F F U 20 D D F F F F F F F F F F F U 21 D D D F F F F F FF F F F U 22 D F F F F F F F F F F F U U 23 D D F F F F F F F F F F U U24 D D D F F F F F F F F F U U 25 D F F F F F F F F F F U U U 26 D D F FF F F F F F F U U U 27 D D D F F F F F F F F U U U 28 D D D D D D D D DD D D F U 29 D D D D D D D D D D D F F U 30 D D D D D D D D D D F F F U31 D D D D D D D D D D D F U U 32 D D D D D D D D D D F F U U

TABLE 11 33 D D D D D D D D D F F F U U 34 D F U U U U U U U U U U U U35 D D F U U U U U U U U U U U 36 D D D F U U U U U U U U U U 37 D F F UU U U U U U U U U U 33 D D F F U U U U U U U U U U 39 D D D F F U U U UU U U U U 40 D F F F U U U U U U U U U U 41 D D F F F U U U U U U U U U42 D D D F F F U U U U U U U U 43 D D D D D D D D D F F F F U 44 D D D DD D F F F F F F U U 45 D D D D D D F F U U U U U U

TABLE 12 46 D D D D D F U D D D D D F U 47 D D F U U U U D D F U U U U48 D F U U U U U D F U U U U U 49 D D D D F F U D D D D F F U 50 D D F FU U U D D F F U U U 51 D F F U U U U D F F U U U U 52 D F F F F F U D FF F F F U 53 D D F F F F U D D F F F F U 54 F F F F F F F D D D D D D D55 D D F F F U U U D D D D D D 56-254 Reserved 255  UE determines theslot format for the slot based on TDD-UL-DL-ConfigurationCommon. or TDD-UL-DL-ConfigDedicated and, if any, on detected DCI formats

If a PDCCH monitoring periodicity for DCI format 2_0, provided to the UEfor the search space set S by a higher-layer parametermonitoringSlotPeriodicityAndOffset, is smaller than the duration of aslot format combination that the UE obtains in a PDCCH monitoringoccasion for DCI format 2_0 by a corresponding SFI-index field value,and the UE detects more than one DCI format 2_0 indicating a slot formatfor a slot, the UE expects each of the more than one DCI format 2_0 toindicate the same (slot) format for the slot.

The UE does not expect to be configured to monitor a PDCCH for DCIformat 2_0 on a second serving cell that uses a larger SCS than theserving cell.

For an unpaired spectrum operation of the UE on a serving cell, the UEis provided, by a higher-layer parameter subcarrierSpacing, with areference SCS configuration μ_(SFI) for each slot format in acombination of slot formats indicated by an SFI-index field value in DCIformat 2_0. The UE expects that for a reference SCS configurationμ_(SFI) and for an SCS configuration μ for an active DL BWP or an activeUL BWP, μ≥μ_(SFI). Each slot format in the combination of slot formatsindicated by the SFI-index field value in DCI format 2_0 is applicableto 2^((μ-μ) ^(SFI) ⁾ consecutive slots in the active DL BWP or theactive UL BWP in which the first slot starts at the same time as thefirst slot for the reference SCS configuration μ_(SFI). Each DL orflexible or UL symbol for the reference SCS configuration μ_(SFI)corresponds to 2^((μ-μ) ^(SFI) ⁾ consecutive DL or flexible or ULsymbols for the SCS configuration μ.

For a paired spectrum operation of the UE on a serving cell, theSFI-index field in DCI format 2_0 includes a combination of slot formatsfor a reference DL BWP and a combination of slot formats for a referenceUL BWP of the serving cell. The UE is provided with a reference SCSconfiguration μ_(SFI) for each slot format in the combination of slotformats indicated by the value. For the reference SCS configurationμ_(SFI) and an SCS configuration μ for the active DL BWP or the activeUL BWP, the UE expects that μ≥μ_(SFI). The UE is provided, by ahigher-layer parameter subcarrierSpacing, with a reference SCSconfiguration μ_(SFI,DL) for the combination of slot formats indicatedby the SFI-index field value in DCI format 2_0 for the reference DL BWPof the serving cell. The UE is provided, by a higher-layer parametersubcarrierSpacing2, with a reference SCS configuration μ_(SFI,UL) forthe combination of slot formats indicated by the SFI-index field valuein DCI format 2_0 for the reference UL BWP of the serving cell. Ifμ_(SFI,DL)≥μ_(SFI,UL), for each 2^((μ) _(SFI),DL^(-μ) ^(SFI,UL) ⁾ by avalue of the higher-layer parameter slotFormats, the value of thehigher-layer parameter slotFormats is determined based on a value of thehigher-layer parameter slotFormatCombinationId in the higher-layerparameter slotFormatCombination, the value of the higher-layer parameterslotFormatCombinationId is set based on the value of the SFI-index fieldvalue in DCI format 2_0, the first 2^((μ) ^(SFI,DL) ^(-μ) ^(SFI,UL) ⁾values for the combination of slot formats are applicable to thereference DL BWP, and the next value is applicable to the reference ULBWP. If μ_(SFI,DL)<μ_(SFI,UL), for each 2^((μ) ^(SFI,UL) ^(-μ) ^(SFI,DL)⁾+1 value provided by the higher-layer parameter slotFormats, the firstvalue for the combination of slot formats is applicable to the referenceDL BWP and the next 2^((μ) ^(SFI,UL) ^(-μ) ^(SFI,DL) ⁾ values areapplicable to the reference UL BWP.

For a set of symbols of a slot, the UE does not expect to detect DCIformat 2_0 with an SFI-index field value indicating the set of symbolsin the slot as UL and to detect DCI format 1_0, DCI format 1_1, or DCIformat 0_1 indicating to the UE to receive a PDSCH or a CSI-RS in theset of symbols of the slot.

For a set of symbols of a slot, the UE does not expect to detect DCIformat 2_0 with an SFI-index field value indicating the set of symbolsin the slot as DL and to detect DCI format 1_0, DCI format 0_1, DCIformat 1_0, DCI format 1_1, DCI format 2_3, or an RAR UL grantindicating to the UE to transmit a PUSCH, a PUCCH, a PRACH, or an SRS inthe set of symbols of the slot.

For a set of symbols of a slot that are indicated as DL/UL by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon, orTDDUL-DL-ConfigDedicated, the UE does not expect to detect DCI format2_0 with an SFI-index field value indicating the set of symbols of theslot as UL/DL, respectively, or as flexible.

For a set of symbols of a slot indicated to the UE by the higher-layerparameter ssb-PositionsInBurst in a higher-layer parameterSystemInformationBlockType1 or ServingCellConfigCommon for reception ofSS/PBCH blocks, the UE does not expect to detect DCI format 2_0 with anSFI-index field value indicating the set of symbols of the slot as UL.

For a set of symbols of a slot indicated to the UE by a higher-layerparameter prach-ConfigurationIndex in a higher-layer parameterRACH-ConfigCommon for PRACH transmissions, the UE does not expect todetect DCI format 2_0 with an SFI-index field value indicating the setof symbols of the slot as DL.

For a set of symbols of a slot indicated to the UE by a higher-layerparameter pdcch-ConfigSIB1 in MIB for a CORESET for a Type0-PDCCH CSSset, the UE does not expect to detect DCI format 2_0 with an SFI-indexfield value indicating the set of symbols of the slot as UL.

For a set of symbols of a slot indicated to the UE as flexible by thehigher-layer parameter TDD-UL-DL-ConfigurationCommon and thehigher-layer parameter TDD-UL-DL-ConfigDedicated, or when thehigher-layer parameter TDD-UL-DL-ConfigurationCommon and thehigher-layer parameter TDD-UL-DL-ConfigDedicated are not provided to theUE, if the UE detects DCI format 2_0 providing a slot formatcorresponding to a slot format value other than 255,

-   -   if one or more symbols in the set of symbols are symbols in a        CORESET configured for the UE for PDCCH monitoring, the UE        receives a PDCCH in the CORESET only if an SFI-index field value        in DCI format 2_0 indicates that the one or more symbols are DL        symbols.    -   if the SFI-index field value in DCI format 2_0 indicates the set        of symbols of the slot as flexible and the UE detects DCI format        1_0, DCI format 1_1, or DCI format 0_1 indicating to the UE to        receive a PDSCH or a CSI-RS in the set of symbols of the slot,        the UE receives a PDSCH or a CSI-RS in the set of symbols of the        slot.    -   if the SFI-index field value in DCI format 2_0 indicates the set        of symbols of the slot as flexible and the UE detects DCI format        0_0, DCI format 0_1, DCI format 1_0, DCI format 1_1, DCI format        2_3, or an RAR UL grant indicating to the UE to transmit a        PUSCH, a PUCCH, a PRACH, or an SRS in the set of symbols of the        slot, the UE transmits the PUSCH, PUCCH, PRACH, or SRS in the        set of symbols of the slot.        -   if the SFI-index field value in DCI format 2_0 indicates the            set of symbols of the slot as flexible, and the UE does not            detect DCI format 1_0, DCI format 1_1, or DCI format 0_1            indicating to the UE to receive a PDSCH or a CSI-RS, or the            UE does not detect DCI format 0_0, DCI format 0_1, DCI            format 1_0, DCI format 1_1, DCI format 2_3, or an RAR UL            grant indicating to the UE to transmit a PUSCH, a PUCCH, a            PRACH, or an SRS in the set of symbols of the slot, the UE            does not transmit or receive a signal in the set of symbols            of the slot.    -   if the UE is configured by the higher layer to receive a PDSCH        or a CSI-RS in the set of symbols of the slot, the UE receives        the PDSCH or the CSI-RS in the set of symbols of the slot, only        if the SFI-index field value in DCI format 2_0 indicates the set        of symbols of the slot as DL.    -   if the UE is configured by the higher layer to transmit a PUCCH,        a PUSCH, or a PRACH in the set of symbols of the slot, the UE        transmits the PUCCH, or the PUSCH, or the PRACH in the slot only        if the SFI-index field value in DCI format 2_0 indicates the set        of symbols of the slot as UL.    -   if the UE is configured by the higher layer to transmit an SRS        in the set of symbols of the slot, the UE transmits the SRS only        in a subset of symbols from the set of symbols of the slot        indicated as UL symbols by the SFI-index field value in DCI        format 2_0.    -   the UE does not expect to detect an SFI-index field value in DCI        format 2_0 indicating the set of symbols of the slot as DL and        also detect DCI format 00, DCI format 0_1, DCI format 1_0, DCI        format 1_1, DCI format 2_3, or an RAR UL grant indicating to the        UE to transmit an SRS, a PUSCH, a PUCCH, or a PRACH, in one or        more symbols from the set of symbols of the slot.    -   the UE does not expect to detect an SFI-index field value in DCI        format 2_0 indicating the set of symbols of the slot as DL or        flexible, if the set of symbols of the slot includes symbols        corresponding to any repetition of a PUSCH transmission        activated by a UL Type 2 grant PDCCH.    -   the UE does not expect to detect an SFI-index field value in DCI        format 2_0 indicating the set of symbols of the slot as UL and        also detect DCI format 1_0 or DCI format 1_1 or DCI format 0_1        indicating to the UE to receive a PDSCH or a CSI-RS in one or        more symbols from the set of symbols of the slot.

If the UE is configured by the higher layer to receive a CSI-RS or aPDSCH in a set of symbols of a slot and detects DCI format 2_0indicating a subset of symbols from the set of symbols as UL or flexibleor DCI format 00, DCI format 0_1, DCI format 1_0, DCI format 1_1, or DCIformat 2_3 indicating to the UE to transmit a PUSCH, a PUCCH, an SRS, ora PRACH in at least one symbol in the set of the symbols, the UE cancelsthe CSI-RS reception or the PDSCH reception in the slot.

If the UE is configured by the higher layer to transmit an SRS, a PUCCH,or a PUSCH, or a PRACH in a set of symbols of a slot and detects DCIformat 2_0 with a slot format value indicating a subset of symbols fromthe set of symbols as DL or flexible, or DCI format 1_0, DCI format 1_1,or DCI format 0_1 indicating to the UE to receive a CSI-RS or a PDSCH inat least one symbol in the set of symbols, then

-   -   the UE does not expect to cancel the signal transmission in the        subset of symbols that occur, relative to a last symbol of a        CORESET in which the UE detects DCI format 2_0, DCI format 1_0,        DCI format 1_1, or DCI format 0_1, after fewer symbols than a        PUSCH preparation time T_(proc,2) for the corresponding PUSCH        processing capability.    -   the UE cancels the PUCCH, or PUSCH, or PRACH transmission in the        remaining symbols in the set of symbols and cancels the SRS        transmission in the remaining symbols in the set of symbols.

If the UE does not detect DCI format 2_0 indicating the set of symbolsof the slot as flexible or UL or DCI format 0-_0, DCI format 0_1, DCIformat 1_0, DCI format 1_1, or DCI format 2_3 indicating to the UE totransmit an SRS, a PUSCH, a PUCCH, or a PRACH in the set of symbols, theUE assumes that flexible symbols in a CORESET configured for the UE forPDCCH monitoring are DL symbols.

For a set of symbols of a slot that are indicated as flexible by thehigher-layer parameters TDD-UL-DL-ConfigurationCommon andTDD-UL-DL-ConfigDedicated, or when the higher-layer parameters TDD-ULDL-ConfigurationCommon, and TDD-UL-DL-ConfigDedicated are not providedto the UE, if the UE does not detect DCI format 2_0 providing a slotformat for the slot,

-   -   the UE receives a PDSCH or a CSI-RS in the set of symbols of the        slot, if the UE receives a corresponding indication by DCI        format 1_0, DCI format 1_1, or DCI format 0_1.    -   the UE transmits a PUSCH, a PUCCH, a PRACH, or an SRS in the set        of symbols of the slot, if the UE receives a corresponding        indication by DCI format 0_0, DCI format 0_1, DCI format 1_0,        DCI format 1_1, or DCI format 2_3.    -   the UE may receive a PDCCH.    -   if the UE is configured by the higher layer to receive a PDSCH        or a CSI-RS in the set of symbols of the slot, the UE does not        receive the PDSCH or the CSI-RS in the set of symbols of the        slot.    -   if the UE is configured by the higher layer to transmit an SRS,        a PUCCH, a PUSCH, or a PRACH in the set of symbols of the slot,        -   the UE does not transmit the PUCCH, the PUSCH, or the PRACH            in the slot and does not transmit the SRS in symbols from            the set of symbols in the slot, if any, starting from a            symbol that is a number of symbols equal to the PUSCH            preparation time N2 for the corresponding PUSCH timing            capability after a last symbol of a CORESET where the UE is            configured to monitor PDCCH for DCI format 2_0.    -   The UE does not expect to cancel the transmission of the SRS, or        the PUCCH, or the PUSCH, or the PRACH in symbols from the set of        symbols in the slot, if any, starting before a symbol that is a        number of symbols equal to the PUSCH preparation time N₂ for the        corresponding PUSCH timing capability after a last symbol of a        CORESET where the UE is configured to monitor a PDCCH for DCI        format 2_0.

1.9. RRM Measurement

While radio resource management (RRM) measurement is described below inthe context of the LTE system, those skilled in the art could easilyunderstand that the RRM measurement may be extended to thenext-generation system (e.g., NR).

The LTE system supports RRM operations including power control,scheduling, cell search, cell reselection, handover, radio link orconnection monitoring, and connection establishment/re-establishment. Aserving cell may request RRM measurement information required for an RRMoperation to a UE. In the LTE system, the UE may measure and reportmainly information such as cell search information, reference signalreceived power (RSRP), and reference signal received quality (RSRQ).Specifically in the LTE system, the UE may receive ‘measConfig’ in ahigher-layer signal for RRM measurement from the serving cell andmeasure RSRP or RSRQ according to information of ‘measConfig’.

In the LTE system, RSRP, RSRQ, and received signal strength indicator(RSSI) are defined as follows.

RSRP is defined as the linear average over the power contributions (in[W]) of the resource elements that carry cell-specific reference signalswithin the considered measurement frequency bandwidth. For RSRPdetermination, the cell-specific reference signals R₀ shall be used. Ifreceiver diversity is in use by the UE, the reported value shall not belower than the corresponding MB SFN RSRP of any of the individualdiversity branches. If the UE can reliably detect that R₁ is available,it may use R₁ in addition to R₀ to determine RSRP.

The reference point for the RSRP shall be the antenna connector of theUE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding RSRP of any of the individual diversitybranches.

RSRQ is defined as the ratio N×RSRP/(E-UTRA carrier RSSI), where N isthe number of RB's of the E-UTRA carrier RSSI measurement bandwidth. Themeasurements in the numerator and denominator shall be made over thesame set of resource blocks.

E-UTRA carrier RSSI comprises the linear average of the total receivedpower (in [W]) observed only in OFDM symbols containing referencesymbols for antenna port 0, in the measurement bandwidth, over N numberof resource blocks by the UE from all sources, including co-channelserving and non-serving cells, adjacent channel interference, thermalnoise etc. If higher-layer signaling indicates certain subframes forperforming RSRQ measurements, then RSSI is measured over all OFDMsymbols in the indicated subframes.

The reference point for the RSRQ shall be the antenna connector of theUE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding RSRQ of any of the individual diversitybranches.

RSSI is defined as the received wideband power, including thermal noiseand noise generated in the receiver, within the bandwidth defined by thereceiver pulse shaping filter.

The reference point for the measurement shall be the antenna connectorof the UE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding UTRA carrier RSSI of any of theindividual receive antenna branches.

According to the above definitions, a UE operating in the LTE system maymeasure RSRP in a bandwidth indicated by an allowed measurementbandwidth-related information element (IE) transmitted in systeminformation block type 3 (SIB3) in the case of intra-frequencymeasurement. In the case of inter-frequency measurement, the UE maymeasure RSRP in a bandwidth corresponding to one of 6, 15, 25, 50, 75,and 100 RBs, indicated by an allowed measurement bandwidth-related IE insystem information block type 5 (SIB5). Alternatively, without the IE,the UE may measure RSRP in a total DL system frequency band by default.

When the UE receives information about an allowed measurement bandwidth,the UE may measure RSRP freely within the corresponding value,considering that the corresponding value is a maximum measurementbandwidth. However, when the serving cell transmits an IE defined aswideband-RSRQ (WB-RSRQ) to the UE and sets the allowed measurementbandwidth to 50 or more RBs, the UE should calculate an RSRP value forthe total allowed measurement bandwidth. In regards to RSSI, the UEmeasures RSSI in a frequency band that the receiver of the UE hasaccording to the definition of an RSSI bandwidth.

According to the above definitions, a UE operating in the LTE system maybe allowed to measure RSRP in a bandwidth corresponding to one of 6, 15,25, 50, 75, and 100 RBs by an allowed measurement bandwidth-related IEtransmitted in 51133 in the case of intra-frequency measurement. In thecase of inter-frequency measurement, the UE may be allowed to measureRSRP in a bandwidth corresponding to one of 6, 15, 25, 50, 75, and 100RBs by an allowed measurement bandwidth-related IE in SIB5.Alternatively, without the IE, the UE may measure RSRP in a total DLsystem frequency band by default.

When the UE receives the allowed measurement bandwidth-related IE, theUE may measure RSRP freely within the corresponding value, consideringthat the corresponding value is a maximum measurement bandwidth.However, when the serving cell transmits an IE defined as WB-RSRQ andsets an allowed measurement bandwidth to 50 or more RBs, the UE shouldcalculate an RSRP value for the total allowed measurement bandwidth. Inregards to RSSI, the UE measures RSSI in a frequency band that thereceiver of the UE has according to the definition of an RSSI bandwidth.

2. Unlicensed Band System

FIGS. 17A and 17B illustrate an exemplary wireless communication systemsupporting an unlicensed band, which is applicable to the presentdisclosure.

In the following description, a cell operating in a licensed band(hereinafter, referred to as L-band) is defined as an L-cell, and acarrier of the L-cell is defined as a (DL/UL) LCC. In addition, a celloperating in an unlicensed band (hereinafter, referred to as a U-band)is defined as a U-cell, and a carrier of the U-cell is defined as a(DL/UL) UCC. The carrier/carrier-frequency of the cell may refer to theoperating frequency (e.g., center frequency) of the cell. A cell/carrier(e.g., CC) is collectively referred to as a cell.

As illustrated in FIG. 17A, when the UE and the BS transmit and receivesignals in carrier-aggregated LCC and UCC, the LCC may be configured asa primary CC (PCC) and the UCC may be configured as a secondary CC(SCC).

As illustrated in FIG. 17B, the UE and the BS may transmit and receivesignals in one UCC or a plurality of carrier-aggregated LCC and UCC.That is, the UE and the BS may transmit and receive signals only in theUCC(s) without the LCC.

The above-described operation of transmitting and receiving a signal inan unlicensed band according to the present disclosure may be performedbased on all the deployment scenarios described above (unless otherwisestated).

2.1. Radio Frame Structure for Unlicensed Band

Frame structure type 3 of LTE (see FIG. 3 ) or the NR frame structure(see FIG. 7 ) may be used for operation in the unlicensed band. Theconfiguration of OFDM symbols occupied for a UL/DL signal transmissionin the frame structure for the unlicensed band may be configured by theBS. Herein, an OFDM symbol may be replaced with an SC-FDM(A) symbol.

For a DL signal transmission in the unlicensed band, the BS may indicatethe configuration of OFDM symbols used in subframe #n to the UE bysignaling. In the following description, a subframe may be replaced witha slot or a TU.

Specifically, in the LTE system supporting the unlicensed band, the UEmay assume (or identify) the configuration of OFDM symbols occupied insubframe #n by a specific field (e.g., a Subframe configuration for LAAfield) in DCI received in subframe #n−1 or subframe #n from the BS.

Table 13 illustrates an exemplary method of indicating the configurationof OFDM symbols used for transmission of a DL physical channel and/orphysical signal in a current and/or next subframe by the Subframeconfiguration for LAA field.

TABLE 13 Value of  

 Subframe Configuration of configuration occupied OFDM for LAA 

  symbols (current field in current subframe, next subframe subframe)0000 (—, 14) 0001 (—, 12) 0010 (—, 11) 0011 (—. 10) 0100 (—, 9) 0101 (—,6) 0110 (—, 3) 0111 (14, *) 1000 (12, —) 1001 (11, —) 1010 (10, —) 1011 (9, —) 1100  (6, —) 1101  (3, —) 1110 reserved 1111 reserved NOTE: (—,Y) means UE may assume the first Y symbols are occupied in next subframeand other symbols in the next subframe are not occupied. (X, —) means UEmay assume the first X symbols are occupied in current subframe andother symbols in the current subframe are not occupied. (X, *) means UEmay assume the first X symbols are occupied in current subframe, and atleast the first OFDM symbol of the next subframe is not occupied.

indicates data missing or illegible when filed

For a UL signal transmission in the unlicensed band, the BS may transmitinformation about a UL transmission duration to the UE by signaling.

Specifically, in the LTE system supporting the unlicensed band, the UEmay acquire ‘UL duration’ and ‘UL offset’ information for subframe #nfrom a ‘UL duration and offset’ field in detected DCI.

Table 14 illustrates an exemplary method of indicating a UL offset andUL duration configuration by the UL duration and offset field in the LTEsystem.

TABLE 14 Value of  

 UL duration and UL offset, l UL duration, d offset 

  field (in subframes) (in subframes) 00000 Not Not configuredconfigured 00001 1 1 00010 1 2 00011 1 3 00100 1 4 00101 1 5 00110 1 600111 2 1 01000 2 2 01001 2 3 01010 2 4 01011 2 5 01100 2 6 01101 3 101110 3 2 01111 3 3 10000 3 4 10001 3 5 10010 3 6 10011 4 1 10100 4 210101 4 3 10110 4 4 10111 4 5 11000 4 6 11001 6 1 11010 6 2 11011 6 311100 6 4 11101 6 5 11110 6 6 11111 reserved reserved

indicates data missing or illegible when filed

For example, when the UL duration and offset field configures (orindicates) UL offset l and UL duration d for subframe #n, the UE may notneed to receive a DL physical channel and/or physical signal in subframe#n+l+i (i=0, 1, . . . , d−1).

2.2. DL Channel Access Procedure (DL CAP)

For a DL signal transmission in the unlicensed band, the BS may performa DL CAP for the unlicensed band. On the assumption that the BS isconfigured with a PCell that is a licensed band and one or more SCellswhich are unlicensed bands, a DL CAP operation applicable to the presentdisclosure will be described below in detail, with the unlicensed bandsrepresented as licensed assisted access (LAA) SCells. The DL CAPoperation may be applied in the same manner even when only an unlicensedband is configured for the BS.

2.2.1. Channel Access Procedure for Transmission(s) IncludingPDSCH/PDCCH/EPDCCH

The BS senses whether a channel is in an idle state for a slot durationof a defer duration T_(d). After a counter N is decremented to 0 in step4 as described later, the BS may perform a transmission including aPDSCH/PDCCH/EPDCCH on a carrier on which the next LAA SCell(s)transmission is performed. The counter N may be adjusted by sensing thechannel for an additional slot duration according to the followingprocedure.

1) Set N=N_(init) where N_(init) is a random number uniformlydistributed between 0 and CW_(p), and go to step 4.

2) If N>0 and the BS chooses to reduce the counter, set N=N−1.

3) Sense the channel for an additional slot duration, and if theadditional slot duration is idle, go to step 4. Else, go to step 5.

4) If N=0, stop. Else, go to step 2.

5) Sense the channel until a busy slot is detected within the additionaldefer duration T_(d) or all slots of the additional defer duration T_(d)are sensed as idle.

6) If the channel is sensed as idle for all slot durations of theadditional defer duration T_(d), go to step 4. Else, go to step 5.

The above-described CAP for a transmission including aPDSCH/PDCCH/EPDCCH of the BS may be summarized as follows.

FIG. 18 is a flowchart illustrating a CAP for transmission in anunlicensed band, which is applicable to the present disclosure.

For a DL transmission, a transmission node (e.g., a BS) may initiate theCAP to operate in LAA SCell(s) which is unlicensed band cell(s) (S2110).

The BS may randomly select a backoff counter N within a contentionwindow (CW) according to step 1. N is set to an initial value, N_(init)(S2120). N_(init) is a random value selected from among the valuesbetween 0 and CW_(p).

Subsequently, if the backoff counter N is 0 in step 4 (Yin S2130), theBS terminates the CAP (S2132). Subsequently, the BS may perform a Txburst transmission including a PDSCH/PDCCH/EPDCCH (S2134). On the otherhand, if the backoff counter N is not 0 (N in S2130), the BS decrementsthe backoff counter N by 1 according to step 2 (S2140).

Subsequently, the BS determines whether the channel of the LAA SCell(s)is in an idle state (S2150). If the channel is in the idle state (YinS2150), the BS determines whether the backoff counter N is 0 (S2130).

On the contrary, if the channel is not idle in step S2150, that is, thechannel is busy (N in S2150), the BS determines whether the channel isin the idle state for a defer duration T_(d) (25 usec or more) longerthan a slot time (e.g., 9 usec) according to step 5 (S2160). If thechannel is idle for the defer duration (Yin S2170), the BS may resumethe CAP.

For example, if the backoff counter N_(init) is 10 and then reduced to5, and the channel is determined to be busy, the BS senses the channelfor the defer duration and determines whether the channel is idle. Ifthe channel is idle for the defer duration, the BS may resume the CAPfrom a backoff counter value 5 (or from a backoff counter value 4 afterdecrementing the backoff counter value by 1).

On the other hand, if the channel is busy for the defer duration (N inS2170), the BS re-performs step S2160 to check again whether the channelis idle for a new defer duration.

In the above procedure, if the BS does not perform the transmissionincluding the PDSCH/PDCCH/EPDCCH on the carrier on which a LAA SCell(s)transmission is performed after step 4, the BS may perform thetransmission including the PDSCH/PDCCH/EPDCCH on the carrier, when thefollowing conditions are satisfied:

When the BS is prepared to transmit the PDSCH/PDCCH/EPDCCH and thechannel is sensed as idle for at least a slot duration T_(sl), or forall slot durations of the defer duration T_(d) immediately before thetransmission; and

On the contrary, when the BS does not sense the channel as idle for theslot duration T_(sl) or for any of the slot durations of the deferduration T_(d) immediately before the intended transmission, the BSproceeds to step 1 after sensing the channel as idle for a slot durationof the defer duration T_(d).

The defer duration T_(d) includes a duration of T_(f) (=16 us)immediately followed by m_(p) consecutive slot durations where each slotduration T_(sl) is 9 us, and T_(f) includes an idle slot duration T_(sl)at the start of T_(f).

If the BS senses the channel for the slot duration T_(sl) and powerdetected by the BS for at least 4 us within the slot duration is lessthan an energy detection threshold X_(Thresh), the slot duration T_(sl)is considered to be idle. Otherwise, the slot duration T_(sl) isconsidered to be busy.

CW_(min,p)≤CW_(p)≤CW_(max,p) represents a contention window. CW_(p)adjustment will be described in section 2.2.3.

CW_(min,p) and CW_(max,p) are chosen before step 1 of the aboveprocedure.

m_(p), CW_(min,p), and CW_(max,p) are based on a channel access priorityclass associated with the transmission of the BS (see Table 15 below).

X_(Thresh) is adjusted according to section 2.2.4.

TABLE 15 Channel Access Priority Class (p) m_(p) CW_(min,p) CW_(max,p)T 

 _(,p) allowed CW_(p) sizes 1 1 3 7 2 ms {3, 7} 2 1 7 15 3 ms {7, 15} 33 15 63 8 or 10 ms {15, 31, 63} 4 7 15 1023 8 or 10 ms {15, 31, 63, 127,255, 511, 1023}

indicates data missing or illegible when filed

If the BS performs a discovery signal transmission which does notinclude a PDSCH/PDCCH/EPDCCH when N>0 in the above procedure, the BSdoes not decrement N for a slot duration overlapping with the discoverysignal transmission.

The BS does not continuously perform transmissions on the channel, for aperiod exceeding T_(mcot,p) as given in Table 15 on the carrier on whichan LASS SCell transmission is performed.

For p=3 and p=4 in Table 15, if the absence of any other technologysharing the carrier may be guaranteed on a long term basis (e.g., bylevel of regulation), T_(mcot,p)=10 ms and otherwise, T_(mcot,p)=8 ms.

2.2.2. Channel Access Procedure for Transmissions Including DiscoverySignal Transmission(S) and not Including PDSCH

If the transmission duration of the BS is 1 ms or less, the BS mayperform a transmission including a discovery signal transmission withouta PDSCH on a carrier on which a LAA SCell transmission is performed,immediately after a corresponding channel is sensed as idle for at leasta sensing interval T_(drs) (=25 us). T_(drs) includes a duration ofT_(f)(=16 us) immediately followed by one slot duration T_(sl) (=9 us).T_(f) includes an idle slot duration T_(sl) at the start of T_(f). Ifthe channel is sensed as idle for the slot duration Tars, the channel isconsidered to be idle for T_(drs).

2.2.3. Contention Window Adjustment Procedure

If the BS performs a transmission including a PDSCH associated with achannel access priority class p on a carrier, the BS maintains andadjusts a contention window value CW_(p) by using the followingprocedures before step 1 of the procedure described in section 2.2.1.for the transmission (i.e., before performing a CAP):

1> Set CW_(p)=CW_(min,p) for all priority classes p∈{1, 2, 3, 4}.

2> If at least 80% (z=80%) of HARQ-ACK values corresponding to PDSCHtransmission(s) in a reference subframe k are determined to be NACK, theBS increments CW_(p) for all priority classes p∈{1, 2, 3, 4} to the nexthigher allowed value and remains in step 2. Otherwise, the BS goes tostep 1.

In other words, when the probability that the HARQ-ACK valuescorresponding to the PDSCH transmission(s) in reference subframe k aredetermined to be NACK is at least 80%, the BS increments a CW value setfor each priority class to the next higher value. Alternatively, the BSmaintains the CW value set for each priority class to be an initialvalue.

Reference subframe k is the starting subframe of the most recenttransmission on the carrier made by the BS, for which at least someHARQ-ACK feedback is expected to be available.

The BS adjusts the CW_(p) values for all priority classes p∈{1, 2, 3, 4}only once based on the given reference subframe k.

If CW_(p)=CW_(max,p) the next higher allowed value for the CW_(p)adjustment is CW_(max,p).

The probability Z of determining HARQ-ACK values corresponding to PDSCHtransmission(s) in reference subframe k to be NACK may be determined inconsideration of the following.

-   -   If the transmission(s) of the BS for which HARQ-ACK feedback is        available starts in the second slot of subframe k, HARQ-ACK        values corresponding to PDSCH transmission(s) in subframe k and        additionally, HARQ-ACK values corresponding to PDSCH        transmission(s) in subframe k+1 are used.    -   If HARQ-ACK values correspond to PDSCH transmission(s) in the        same LAA SCell allocated by an (E)PDCCH transmitted in LAA        SCell,    -   If an HARQ-ACK feedback for a PDSCH transmission of the BS is        not detected or if the BS detects a ‘DTX’, ‘NACK/DTX’ or (any)        other state, it is counted as NACK.    -   If the HARQ-ACK values correspond to PDSCH transmission(s) in        another LAA SCell allocated by an (E)PDCCH transmitted in the        LAA SCell,    -   If an HARQ-ACK feedback for a PDSCH transmission of the BS is        detected, ‘NACK/DTX’ or (any) other state is counted as NACK and        the ‘DTX’ state is ignored.    -   If an HARQ-ACK feedback for a PDSCH transmission of the BS is        not detected,    -   If it is expected that the BS will use PUCCH format 1 with        channel selection, the ‘NACK/DTX’ state corresponding to ‘no        transmission’ is counted as NACK, and the ‘DTX’ state        corresponding to ‘no transmission’ is ignored. Otherwise, the        HARQ-ACK for the PDSCH transmission is ignored.    -   If the PDSCH transmission has two codewords, an HARQ-ACK value        for each codeword is considered individually.    -   A bundled HARQ-ACK across M subframes is considered to be M        HARQ-ACK responses.

If the BS performs a transmission which includes a PDCCH/EPDDCH with DCIformat 0A/0B/4A/4B and does not include a PDSCH associated with thechannel access priority class p on a channel starting from time to, theBS maintains and adjusts the competing window size CW_(p) by using thefollowing procedures before step 1 of the procedure described in section2.2.1. for the transmission (i.e., before performing the CAP):

1> Set CW_(p)=CW_(max,p) for all priority classes p∈{1, 2, 3, 4}.

2> If a UE using a type 2 CAP (described in section 2.3.1.2.)successfully receives less than 10% of UL transport blocks (TBs)scheduled by the BS during a time period t₀ and t₀+T_(CO), the BSincrements CW_(p) for all priority classes to the next higher allowedvalue and remains in step 2. Otherwise, the BS goes to step 1.

T_(CO) is calculated according to section 2.3.1.

If CW_(p)=CW_(max,p) is used K times consecutively to generate N_(init),only CW_(p) for a priority class p for CW_(p)=CW_(max,p) used K timesconsecutively to generate N_(init) is reset to CW_(min,p). the BS thenselects K from a set of {1, 2, . . . , 8} values for each priority classp∈{1, 2, 3, 4}.

2.2.4. Energy Detection Threshold Adaptation Procedure

A BS accessing a carrier on which a LAA SCell transmission is performedsets an energy detection threshold X_(Thresh) to a maximum energydetection threshold X_(Thresh_max) or less.

The maximum energy detection threshold X_(Thresh_max) is determined asfollows.

-   -   If the absence of any other technology sharing the carrier may        be guaranteed on a long term basis (e.g., by level of        regulation),

$X_{{Thresh}\_\max} = {\min\begin{Bmatrix}{{T_{\max} + {10{dB}}},} \\X_{r}\end{Bmatrix}}$

-   -   where X_(r) is the maximum energy detection threshold (in dBm)        defined in regulatory requirements, when the regulation is        defined. Otherwise, X_(p)=T_(max)+10 dB.    -   Else,

$X_{{Thresh}\_\max} = {\max\begin{Bmatrix}{{{- 72} + {{10 \cdot \log}10\left( {{BW}{MHz}/20{MHz}} \right){dB}m}},} \\{\min\begin{Bmatrix}{T_{\max},} \\{T_{\max} - T_{A} + \left( {P_{H} + {{10 \cdot \log}10\left( {{BW}{MHz}/20{MHz}} \right)} - P_{TX}} \right.}\end{Bmatrix}}\end{Bmatrix}}$

-   -   Herein, each variable is defined as follows.        -   T_(A)=10 dB for transmission(s) including PDSCH;        -   T_(A)=5 dB for transmissions including discovery signal            transmission(s) and not including PDSCH;        -   P_(H)=23 dBm;        -   P_(TX) is the set maximum eNB output power in dBm for the            carrier;            -   eNB uses the set maximum transmission power over a                single carrier irrespective of whether single carrier or                multi-carrier transmission is employed        -   T_(max) (dBm)=10·log 10(3.16228·10⁻⁸ (mW/MHz)·BWMHz (MHz)):        -   BWMHz is the single carrier bandwidth in MHz.

2.2.5. Channel Access Procedure for Transmission(S) on Multiple Carriers

The BS may access multiple carriers on which a LAA SCell transmission isperformed in one of the following type A or type B procedures.

2.2.5.1. Type A Multi-Carrier Access Procedures

According to the procedure described in this section, the BS performschannel access on each carrier c_(i)∈C where C is a set of intendedcarriers to be transmitted by the BS, i=0, 1, . . . q−1, and q is thenumber of carriers to be transmitted by the BS.

The counter N described in section 2.2.1 (i.e., the counter N consideredin the CAP) is determined for each carrier c_(i), and in this case, thecounter for each carrier is represented as N_(c), is maintainedaccording to section 2.2.5.1.1. or section 2.2.5.1.2.

2.2.5.1.1. Type A1

The counter N described in section 2.2.1 (i.e., the counter N consideredin the CAP) is determined for each carrier c_(i), and the counter foreach carrier is represented as N_(c) _(i) .

In the case where the BS ceases a transmission on one carrier c_(j)∈C,if the absence of any other technology sharing the carrier may beguaranteed on a long term basis (e.g., by level of regulation), the BSmay resume N_(c) _(i) reduction, when an idle slot is detected afterwaiting for a duration of 4·T_(sl) or reinitializing N_(c) _(i) , foreach carrier c_(i) (where c_(i) is different from c_(j), c_(i)≠c_(j)).

2.2.5.1.2. Type A2

The counter N for each carrier c_(j)∈C may be determined according tosection 2.2.1., and is denoted by N_(c) _(j) . Here, c_(j) may mean acarrier having the largest CW_(p) value. For each carrier c_(j), N_(c)_(i) =N_(c) _(j) .

When the BS ceases a transmission on any one carrier for which N_(c),has been determined by the BS, the BS reinitializes N_(c), for allcarriers.

2.2.5.2. Type B Multi-Carrier Access Procedure

A carrier c_(j)∈C may be selected by the BS as follows.

-   -   The BS selects c_(j) uniformly randomly from C before each        transmission on multiple carriers c_(i)∈C, or    -   The BS does not select c_(j) more than once every one second.

Herein, C is a set of carriers to be transmitted by the BS, i=0, 1, . .. q−1, and q is the number of carriers to be transmitted by the BS.

For a transmission on a carrier c_(j), the BS performs channel access onthe carrier c_(j) according to the procedure described in section 2.2.1along with the modification described in section 2.2.5.2.1 or section2.2.5.2.2.

For a transmission on the carrier c_(i)≠c_(j) among the carriersc_(i)∈C,

For each carrier c_(i), the BS senses the carrier c_(i) for at least asensing interval T_(mc)=25 us immediately before the transmission on thecarrier c_(i). The BS may perform a transmission on the carrier c_(i)immediately after sensing that the carrier c_(i) is idle for at leastthe sensing interval T_(mc). When the channel is sensed as idle duringall time periods in which idle sensing is performed on the carrier c_(j)within the given period T_(mc), the carrier c_(i) may be considered tobe idle for T_(mc).

The BS does not continuously perform transmissions on the carrierc_(i)≠c_(j) (c_(i)∈C) for a period exceeding T_(mcot,p) as given inTable 15. T_(mcot,p) is determined using the channel access parameterused for the carrier c_(j).

2.2.5.2.1. Type B1

A single CW_(p) value is maintained for the carrier set C.

To determine CW_(p) for channel access on a carrier c_(j), step 2 in theprocedure described in section 2.2.3. is modified as follows.

-   -   If at least 80% (Z=80%) of HARQ-ACK values corresponding to        PDSCH transmission(s) in reference subframe k of all carriers        c_(i)∈C are determined to be NACK, then CW_(p) for all priority        classes p∈{1, 2, 3, 4} is incremented to the next higher allowed        value. Otherwise, the procedure goes to step 1.

2.2.5.2.2. Type B2 (Type B2)

The CW_(p) value is maintained independently for each carrier c_(i)∈C byusing the procedure described in section 2.2.3. To determine N_(init)for the carrier c_(j), the CW_(p) value of the carrier c_(j1)∈C is used.Here, c_(j1) is a carrier having the largest CW_(p) among all carriersin the set C.

2.3. Uplink Channel Access Procedures

The UE and the BS that schedules a UL transmission for the UE performthe following procedure for access to a channel in which LAA SCelltransmission(s) is performed. On the assumption that the UE and the BSare basically configured with a PCell that is a licensed band and one ormore SCells which are unlicensed bands, a UL CAP operation applicable tothe present disclosure will be described below in detail, with theunlicensed bands represented as LAA SCells. The UL CAP operation may beapplied in the same manner even when only an unlicensed band isconfigured for the UE and the BS.

2.3.1. Channel Access Procedure for Uplink Transmission(s)

The UE may access a carrier on which LAA SCell UL transmission(s) areperformed according to a type 1 or type 2 UL CAP. The type 1 CAP isdescribed in section 2.3.1.1, and the type 2 CAP is described in section2.3.1.2.

If a UL grant that schedules a PUSCH transmission indicates the type 1CAP, the UE performs type 1 channel access to perform a transmissionincluding the PUSCH transmission, unless otherwise stated in thissection.

If the UL grant that schedules the PUSCH transmission indicates the type2 CAP, the UE performs type 2 channel access to perform a transmissionincluding the PUSCH transmission, unless otherwise stated in thissection.

The UE performs type 1 channel access for an SRS transmission that doesnot include a PUSCH transmission. A UL channel access priority class p=1is used for the SRS transmission that does not include a PUSCH.

TABLE 16 Channel Access Priority Class (p) m_(p) CW_(min,p) CW_(max,p)T 

 _(,p) allowed CW_(p) sizes 1 2 3 7 2 ms {3, 7} 2 2 7 15 4 ms {7, 15} 33 15 1023 6 ms {15, 31, 63, 127, or 10 ms 255, 511, 1023} 4 7 15 1023 6ms {15, 31, 63, 127, or 10 ms 255, 511, 1023} NOTE1: For p = 3, 4, T 

  = 10 ms if the higher layer parameter  

 absenceOfAnyOtherTechnology-r14 

  indicates TRUE, otherwise, T 

  = 6 ms. NOTE 2: When T 

  = 6 ms it may be increased to 8 ms by inserting one or more gaps. Theminimum duration of a gap shall be 100 μs The maximum duration beforeincluding any such gap shall be 6 ms.

indicates data missing or illegible when filed

When the ‘UL configuration for LAA’ field configures ‘UL offset’ l and‘UL duration’ d for subframe n,

If the end of a UE transmission occurs in or before subframe n+l+d−1,the UE may use the type 2 CAP for transmission in subframe n+l+i (wherei=0, 1 . . . d−1).

If the UE is scheduled to perform a transmission including a PUSCH in asubframe set n₀, n₁, . . . , n_(w-1) by using PDCCH DCI format 0B/4B,and the UE may not perform channel access for transmission in subframen_(k), the UE should attempt to make a transmission in subframe n_(k+1)according to a channel access type indicated by DCI. k∈{0, 1, . . . w−2}and w is the number of scheduled subframes indicated by the DCI.

If the UE is scheduled to perform a transmission including a PUSCHwithout gaps in the subframe set n₀, n₁, . . . , n_(w-1) by using one ormore of PDCCH DCI formats 0A/0B/4A/4B, and performs a transmission insubframe n_(k) after accessing a carrier according to the type 1 or type2 CAP, the UE may continue the transmission in a subframe after n_(k)where k∈{0, 1, . . . w−1}.

If the start of the UE transmission in subframe n+1 immediately followsthe end of the UE transmission in subframe n, the UE does not expectthat a different channel access type will be indicated for thetransmission in the subframe.

If the UE is scheduled to perform a transmission without gaps by usingone or more of PDCCH DCI formats 0A/0B/4A/4B, stops the transmissionduring or before subframe n_(k1) (where k1∈{0, 1, . . . w−2}) andcontinuously senses the corresponding channel as idle after stopping thetransmission, the UE may perform the transmission in the type 2 CAPafter subframe n_(k2) (where k2∈{1, . . . w−1}). If the channel is notsensed continuously as idle by the UE after the UE stops thetransmission, the UE may perform the transmission in the type 1 CAP of aUL channel access priority class indicated by DCI corresponding tosubframe n_(k2) after subframe n_(k2) (where k2∈{1, . . . w−1}).

If the UE receives a UL grant, DCI indicates the UE to start a PUSCHtransmission in subframe n by using the type 1 CAP, and the UE has anongoing type 1 CAP before subframe n,

-   -   If a UL channel access priority class value p1 used for the        ongoing type 1 CAP is equal to or greater than a UL channel        access priority class value p2 indicated by the DCI, the UE may        perform the PUSCH transmission by accessing a carrier in the        ongoing type 1 CAP.    -   If the UL channel access priority class value p1 used for the        ongoing type 1 CAP is less than the UL channel access priority        class value p2 indicated by the DCI, the UE terminates the        ongoing type 1 CAP.

If the UE is scheduled to transmit on a carrier set C in subframe n, aUL grant scheduling a PUSCH transmission on the carrier set C indicatesthe type 1 CAP, the same ‘PUSCH starting position’ is indicated for allcarriers of the carrier set C, and the carrier frequencies of thecarrier set C are a subset of a preset carrier frequency set,

-   -   The UE may perform a transmission on a carrier c_(i)∈C in the        type 2 CAP.    -   If the type 2 CAP has been performed on the carrier c_(i)        immediately before the UE transmission on a carrier c_(i)∈C, and    -   If the UE has accessed the carrier c_(j) by using the type 1        CAP,    -   Before performing the type 1 CAP on any one carrier in the        carrier set C, the UE uniformly randomly selects the carrier        c_(j) from the carrier set C.

When the BS has transmitted on the carrier according to the CAPdescribed in section 2.2.1, the BS may indicate the type 2 CAP by DCI ina UL grant that schedules a transmission including a PUSCH on thecarrier in subframe n.

Alternatively, when the BS has transmitted on the carrier according tothe CAP described in section 2.2.1, the BS may indicate that the type 2CAP is available for the transmission including the PUSCH on the carrierin subframe n by the ‘UL Configuration for LAA’ field.

Alternatively, when subframe n occurs within a time period starting fromto and ending at t₀+T_(CO), the BS may schedule the transmissionincluding the PUSCH on the carrier within subframe n following atransmission of a duration T_(short_ul)=25 us from the BS.T_(CO)=T_(mcot,p)+T_(g) and each variable may be defined as follows.

-   -   t0: a time instant at which the BS starts a transmission.    -   T_(mcot,p): determined by the BS according to section 2.2.    -   T_(g): the total period of all gap periods exceeding 25 us        occurring between a DL transmission of the BS starting from to        and a UL transmission scheduled by the BS and between two UL        transmissions scheduled by the BS.

If the UL transmissions are scheduled in succession, the BS schedulesthe UL transmissions between consecutive subframes in to and t₀+T_(CO).

For the UL transmission on the carrier following the transmission of theBS on the carrier within the duration T_(short_ul)=25 us, the UE mayperform the type 2 CAP for the UL transmission.

If the BS indicates the type 2 CAP for the UE by DCI, the BS indicates achannel access priority class used to obtain access to the channel inthe DCI.

2.3.1.1. Type 1 UL Channel Access Procedure

After sensing that the channel is idle for a slot duration of a deferduration T_(d) and the counter N becomes 0 in step 4, the UE may performa transmission using the type 1 CAP. The counter N is adjusted bysensing the channel for additional slot duration(s) according to thefollowing procedure.

1) Set N=N_(init) where N_(init) is a random number uniformlydistributed between 0 and CW_(p), and go to step 4.

2) If N>0 and the BS chooses to decrement the counter, set N=N−1.

3) Sense the channel for an additional slot duration, and if theadditional slot duration is idle, go to step 4. Else, go to step 5.

4) If N=0, stop. Else, go to step 2.

5) Sense the channel during all slot durations of an additional deferduration T_(d).

6) If the channel is sensed as idle during the slot durations of theadditional defer duration T_(d), go to step 4. Else, go to step 5.

The above-described type 1 UL CAP of the UE may be summarized asfollows.

For a UL transmission, a transmission node (e.g., a UE) may initiate theCAP to operate in LAA SCell(s) which is an unlicensed band cell (S2110).

The UE may randomly select a backoff counter N within a CW according tostep 1. N is set to an initial value N_(init) (S2120). N_(init) is avalue selected randomly from among the values between 0 and CW_(p).

Subsequently, if the backoff counter value N is 0 according to step 4(Yin S2130), the UE ends the CAP (S2132). Subsequently, the UE mayperform a Tx burst transmission (S2134). On the other hand, if thebackoff counter value is not 0 (N in S2130), the UE decrements thebackoff counter value by 1 according to step 2 (S2140).

Subsequently, the UE checks whether the channel of the LAA SCell(s) isidle (S2150). If the channel is idle (Yin S2150), the UE checks whetherthe backoff counter value is 0 (S2130).

On the contrary, if the channel is not idle in step S2150, that is, thechannel is busy (N in S2150), the UE checks whether the channel is idlefor a defer duration T_(d) (25 usec or more) longer than a slot time(e.g., 9 usec) according to step 5 (S2160). If the channel is idle forthe defer duration (Yin S2170), the UE may resume the CAP.

For example, if the backoff counter value N_(init) is 10 and the channelis determined to be busy after the backoff counter value is decrementedto 5, the UE determines whether the channel is idle by sensing thechannel for the defer duration. In this case, if the channel is idle forthe defer duration, the UE may perform the CAP again from the backoffcounter value 5 (or from the backoff counter value 4 after decrementingthe backoff counter value by 1), instead of setting the backoff countervalue Nina.

On the other hand, if the channel is busy for the defer duration (N inS2170), the UE re-performs S2160 to check again whether the channel isidle for a new defer duration.

In the above procedure, if the UE does not perform the transmissionincluding the PUSCH on the carrier in which LAA SCell transmission(s) isperformed after step 4 of the afore-described procedure, the UE mayperform the transmission including the PUSCH on the carrier, when thefollowing conditions are satisfied:

-   -   When the UE is prepared to transmit the transmission including        the PUSCH and the channel is sensed as idle during at least the        slot duration T_(sl); and    -   When the channel is sensed as idle during all slot durations of        the defer duration T_(d) immediately before the transmission        including the PUSCH.

On the contrary, when the UE senses the channel for the first time afterbeing prepared for the transmission, if the channel is not sensed asidle during the slot duration T_(sl), or during any of all slotdurations of the defer duration T_(d) immediately before the intendedtransmission including the PUSCH, the UE proceeds to step 1 aftersensing the channel as idle during the slot durations of the deferduration T_(d).

The defer duration T_(d) includes a duration of T_(f) (=16 us)immediately followed by m_(p) consecutive slot durations where each slotduration T_(sl) is 9 us, and T_(f) includes an idle slot duration T_(sl)at the start of T_(f).

If the UE senses the channel during the slot duration T_(sl) and powermeasured by the UE for at least 4 us in the slot duration is less thanan energy detection threshold X_(Thresh), the slot duration T_(sl) isconsidered to be idle. Otherwise, the slot duration T_(sl) is consideredto be busy.

CW_(min,p)≤CW_(p)≤CW_(max,p) represents a contention window, and CW_(p)adjustment is described in detail in section 2.3.2.

CW_(min,p) and CW_(max,p) are chosen before step 1 of the aboveprocedure.

m_(p), CW_(min,p), and CW_(max,p) are determined based on a channelaccess priority class signaled to the UE (see Table 16 below).

X_(Thresh) is adjusted according to section 2.3.3.

2.3.1.2. Type 2 UL Channel Access Procedure

If the UE uses the type 2 CAP for a transmission including a PUSCH, theUE may perform the transmission including the PUSCH immediately aftersensing a channel as idle for at least a sensing durationT_(short_ul)=25 us. T_(short_ul) includes a duration of T_(f)(=16 us)immediately followed by one slot duration T_(sl) (=9 us). T_(f) includesan idle slot duration T_(sl) at the start of T_(f). If the channel issensed as idle during the slot duration T_(short_ul), the channel isconsidered to be idle for T_(short_ul).

2.3.2. Contention Window Adjustment Procedure

If the UE performs a transmission using the type 1 CAP associated with achannel access priority class p on a carrier, the UE maintains andadjusts a contention window value CW_(p) using the following proceduresbefore step 1 of the procedure described in section 2.3.1.1. for thetransmission (i.e., before performing the CAP):

-   -   When a new data indicator (NDI) for at least one HARQ process        related to HARQ_ID_ref is toggled,    -   Set CW_(p)=CW_(min,p) for all priority classes p∈{1, 2, 3, 4}.    -   Else, increment CW_(p) to the next higher allowed value for all        priority classes p∈{1, 2, 3, 4}.

HARQ_ID_ref is the HARQ process ID of a UL-SCH in reference subframen_(ref). Reference subframe n_(ref) is determined as follows.

-   -   When the UE receives a UL grant in subframe n_(g). Here,        subframe n_(w) is the most recent subframe before subframe        n_(g)−3 in which the UE transmits the UL-SCH using the type 1        CAP.    -   If the UE performs a transmission including a UL-SCH without        gaps, starting from subframe no in a subframe n₀, n₁, . . . ,        n_(w), reference subframe n_(ref) is subframe no.

Else, reference subframe n_(ref) is subframe n_(w).

If the UE is scheduled to perform a transmission including a PUSCHwithout gaps in a subframe set n₀, n₁, . . . , n_(w-1) and may notperform any transmission including the PUSCH in the subframe set, the UEmay maintain CW_(p) for all priority classes p∈{1, 2, 3, 4} withoutchanging CW_(p).

If a reference subframe for the recent scheduled transmission is alsosubframe n_(ref) the UE may maintain CW_(p) for all priority classesp∈{1, 2, 3, 4} equal to CW_(p) for a transmission including a PUSCH,which uses the recent scheduled type 1 CAP.

If CW_(p)=CW_(max,p) the next higher allowed value for the CW_(p)adjustment is CW_(max,p).

If CW_(p)=CW_(max,p) is used K times consecutively to generate N_(init),only CW_(p) for a priority class p for CW_(p)=CW_(max,p) used K timesconsecutively to generate N_(init) is reset to CW_(min,p). K is thenselected by the UE from a set of {1, 2, . . . , 8} values for eachpriority class p∈{1, 2, 3, 4}.

2.3.3. Energy Detection Threshold Adaptation Procedure)

A UE accessing a carrier on which a LAA SCell transmission is performedsets an energy detection threshold X_(Thresh) to a maximum energydetection threshold X_(Thresh) max or less.

The maximum energy detection threshold X_(Thresh) max is determined asfollows.

-   -   If the UE is configured with a higher-layer parameter        ‘maxEnergyDetectionThreshold-r14’,    -   X_(Thresh) max is set equal to a value signaled by the        higher-layer parameter.    -   Else,    -   The UE determines X′_(Thresh_max) according to the procedure        described in section 2.3.3.1.    -   If the UE is configured with a higher-layer parameter        maxEnergyDetectionThresholdOffset-r14’,    -   X_(Thresh_max) is set to X′_(Thresh_max) adjusted according to        an offset value signaled by the higher-layer parameter.    -   Else,    -   The UE sets X_(Thresh_max)=X′_(Thresh_max).

2.3.3.1. Default Maximum Energy Detection Threshold ComputationProcedure

If a higher-layer parameter ‘absenceOfAnyOtherTechnology-r14’ indicatesTRUE:

$X_{{Thresh}\_\max}^{\prime} = {\min\begin{Bmatrix}{{T_{\max} + {10{dB}}},} \\X_{r}\end{Bmatrix}}$

where Xr is a maximum energy detection threshold (in dBm) defined inregulatory requirements when the regulation is defined. ElseX_(r)=T_(max)+10 dB,

Else:

$X_{{Thresh}\_\max}^{\prime} = {\max\begin{Bmatrix}{{{- 72} + {{10 \cdot \log}10\left( {{BW}{MHz}/20{MHz}} \right){dB}m}},} \\{\min\begin{Bmatrix}{T_{\max},} \\{T_{\max} - T_{A} + \left( {P_{H} + {{10 \cdot \log}10\left( {{BW}{MHz}/20{MHz}} \right)} - P_{TX}} \right.}\end{Bmatrix}}\end{Bmatrix}}$

Here, each variable is defined as follows.

-   -   T_(A)=10 dB    -   P_(H)=23 dBm;    -   P_(TX) is the set to the value P_(CMAX_H,c) as defined in 3GPP        TS 36.1.01.    -   T_(max) (dBm)=10·log 10(3.16228·10⁻⁸ (mW/MHz)·BWMHz (MHz))        -   BWMHz is the single carrier bandwidth in MHz.

2.4. Subframe/Slot Structure Applicable to Unlicensed Band System

FIG. 19 illustrates a partial TTI or partial subframe/slot applicable tothe present disclosure.

In the Release-13 LAA system, a partial TTI is defined as a DwPTS tomaximize use of MCOT and support continuous transmission in a DL bursttransmission. The partial TTI (or partial subframe) refers to a periodin which a PDSCH signal is transmitted for a length smaller than alegacy TTI (e.g., 1 ms).

In the present disclosure, a starting partial TTI or a starting partialsubframe/slot refers to a form in which some front symbols of a subframeare emptied, and an ending partial TTI or ending partial subframe/slotrefers to a form in which some symbols at the end of a subframe areemptied. (On the other hand, a whole TTI is called a normal TTI or afull TTI.)

FIG. 19 illustrates various forms of the above-described partial TTI.The first drawing of FIG. 19 illustrates the ending partial TTI (orsubframe/slot), and the second drawing of FIG. 19 illustrates thestarting partial TTI (or subframe/slot). In addition, the third drawingof FIG. 22 illustrates a partial TTI (or subframe/slot) configured byemptying some symbols at the start and end of the subframe/slot. In thiscase, a time interval excluding signal transmission in a normal TTI iscalled a transmission gap (TX gap).

While FIG. 19 has been described in the context of a DL operation, thesame thing may be applied to a UL operation. For example, the partialTTI structures illustrated in FIG. 19 may also be applied to PUCCHand/or PUSCH transmission.

3. Various Embodiments of the Present Disclosure

Various embodiments of the present disclosure will be described in moredetail based on the above technical idea. The contents of clause 1 andclause 2 described above may be applied to the various embodiments ofthe present disclosure described below. For example, operations,functions, terms, and so on that are not defined in the followingembodiments of the present disclosure may be performed and describedbased on the contents of clause 1 and clause 2.

As more and more communication devices require larger communicationcapacities, efficient use of a limited frequency band becomes asignificant requirement. In this context, techniques of using anunlicensed band (U-band) in traffic offloading, such as 2.4 GHz mainlyused in the legacy WiFi system or 5 GHz and/or 60 GHz which has newlyattracted attention, are under consideration for a cellularcommunication system such as 3GPP LTE/NR.

To transmit a signal in an unlicensed band, a UE or a BS may performwireless transmission and reception based on contention betweencommunication nodes. That is, when each communication node is totransmit a signal in the unlicensed band, the communication node mayconfirm that another communication node is not transmitting a signal inthe unlicensed band by performing channel sensing before the signaltransmission. This operation may be defined as listen before talk (LBT)or a CAP. Particularly, the operation of checking whether anothercommunication node is transmitting a signal may be defined as carriersensing (CS), and determining that another communication node is nottransmitting a signal is defined as confirming clear channel assessment(CCA).

In an LTE/NR system to which various embodiments of the presentdisclosure are applicable, an eNB/gNB or a UE may also have to performan LBT operation or a CAP for signal transmission in an unlicensed band.In other words, the eNB/gNB or the UE may transmit a signal in theunlicensed band, based on the CAP.

Further, when the eNB/gNB or the UE transmits a signal in the unlicensedband, other communication nodes such as WiFi nodes should not interferewith the eNB/gNB or the UE by performing a CAP. For example, the WiFistandard (e.g., 801.11 ac) specifies a CCA threshold as −62 dBm for anon-WiFi signal and as −82 dBm for a WiFi signal. Accordingly, a station(STA) or access point (AP) operating in conformance to the WiFi standardmay not transmit a signal to prevent interference, for example, whenreceiving a non-WiFi signal at or above −62 dBm.

In the NR system, at least one synchronization signal/physical broadcastchannel block (SS/PBCH block) or synchronization signal block (SSB) issupported. Each SS/PBCH block may correspond to a specific index. Theindex of the SS/PBCH block may be indicated by or known from sequenceinformation in the SS/PBCH block and/or the payload of the SS/PBCHblock. When the index of the SS/PBCH block is obtained from the aboveinformation during initial access, a time-axis boundary such as aframe/subframe/slot and/or an index may be identified from a predefinedrelationship. The UE may also know the index of the frame/subframe/slotbased on a combination with other information in the SS/PBCH block. Thepredefined relationship may refer to a relationship between the indexesof SS/PBCH blocks and time-axis boundaries such asframes/subframes/slots.

For mobility support, the UE should perform radio resourcemanagement/radio link monitoring (RRM/RLM) measurement for a neighboringcell and/or a serving cell. The UE may require such index informationeven when performing RRM/RLM measurement in each SS/PBCH block of the(neighboring) cell.

However, since the unlicensed band is based on random access, the BS andthe UE may attempt signal transmission only when they perform a CAP andsucceed in the CAP before transmitting a signal. That is, since signaltransmission in the unlicensed band depends on a CAP result, an SS/PBCHblock to be transmitted by the BS may not be transmitted at apredetermined timing in the unlicensed band. However, when the SS/PBCHblock (transmission) itself is dropped, it may take a longer time forUEs attempting initial access to camp on the cell. It may also take alonger time for UEs attempting measurement of the servingcell/neighboring cell to obtain a meaningful measurement result.

Because signal transmission depends on a CAP result in the unlicensedband, the UE may not identify when the BS actually succeeds in a CAP andstarts to transmit an SSB/PBCH block. In other words, the UE may nothave knowledge of the starting time of the SSB/PBCH block transmission,thereby suffering from ambiguity.

According to various embodiments of the present disclosure describedbelow, CAP failure may increase the number of transmission occasions ofan SSB/PBCH block. In addition, according to various embodiments of thepresent disclosure, the above-described ambiguity may be eliminated.

Various embodiments of the present disclosure described below relate toa method of transmitting and receiving an SS/PBCH block by a BS and aUE, when a CAP for transmitting the SS/PBCH block in an unlicensed bandis failed. Particularly, the various embodiments of the presentdisclosure described below relate to a method of performing RRMmeasurement and a method of obtaining the index/boundary of a frame/slotby a UE, based on (or in consideration of) the SS/PBCH blocktransmission/reception method.

In the description of various embodiments of the present disclosure,when it is said that a BS has succeeded in a CAP, this may mean thatwhen transmitting a DL signal in an unlicensed band, the BS identifiesthat the unlicensed band is idle based on the CAP and thus starts totransmit the DL signal at a predetermined or predefined timing.

On the contrary, in the description of various embodiments of thepresent disclosure, when it is said that a BS has failed in a CAP, thismay mean that when transmitting a DL signal in an unlicensed band, theBS identifies that the unlicensed band is busy based on the CAP and thusis not capable of starting to transmit the DL signal at a predeterminedor predefined timing.

FIG. 20 is a simplified diagram illustrating a signal flow foroperations of a UE and a BS in an unlicensed band, to which variousembodiments of the present disclosure are applicable.

Referring to FIG. 20 , according to various embodiments of the presentdisclosure, the BS may transmit an SSB based on a CAP and the UE mayreceive the SSB (S2001).

According to various embodiments of the present disclosure, the UE mayobtain cell-related information from the received SSB (S2003).

In an exemplary embodiment, the UE may perform RRM measurement based onthe received SSB (S2005). The UE may then transmit an RRM measurementreport to the BS, and the BS may receive the RRM measurement report(S2007).

In various embodiments of the present disclosure, each of the aboveoperations will be described in detail. Those skilled in the art willclearly understand that unless contradicting each other, the variousembodiments of the present disclosure described below may be combinedfully or partially to implement other various embodiments of the presentdisclosure.

3.1 Method of Transmitting SSB Depending on Success or Failure of CAP

For convenience, a maximum number of SSBs transmittable from a BS isdenoted by L, and a number equal to or less than L is denoted by L′.According to various embodiments of the present disclosure, the BS mayselect only L′ SSBs and attempt to transmit the L′ SSBs. That is, the BSmay transmit an SSB burst set including L or L′ SSBs according tovarious embodiments of the present disclosure.

According to various embodiments of the present disclosure, a window ofa time duration or a size longer or larger than the transmissionduration of L SSBs may be configured, and a plurality of transmissioncandidates for SSB transmission may be configured within this window.For convenience, the time duration or size of the window is denoted byL2. L2 may correspond to a time period during which L SSBs may betransmitted (in time division multiplexing (TDM)). L2 may be representedin time units such as the number of slot and/or msec.

3.1.1. <Option 1. Shifted SSB Transmission>

In option 1, a minimum time interval between available transmissionstarting occasions in an SSB burst set is denoted by L1. L1 may berepresented in time units such as the number of slot and/or msec.

FIG. 21 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure.

Referring to FIG. 21 , according to various embodiments of the presentdisclosure, the time length of a block corresponding to one SSB may beequal to or greater than a time duration occupied by the SSB. In anexemplary embodiment, DL signals/channels (e.g., CSI-RS, PDCCH, PDSCH,and so on) other than the SSB may be multiplexed and transmitted in theremaining resource area of the block other than the time area to whichthe SSB is mapped.

According to various embodiments of the present disclosure, a TU maycorrespond to or relate to a specific time unit. For example, the TU maybe, but not limited to, a slot, a half-slot, or a subframe (1 msec).According to various embodiments of the present disclosure, the value ofL1 and/or L2 may be predefined. Alternatively, according to variousembodiments of the present disclosure, the value of L1 and/or L2 may beset by a UE-specific signal, a cell-specific signal, an L1 signal, or aMAC signal.

According to various embodiments of the present disclosure, when failingin a CAP for an SSB transmission from (at) time t, the BS may performthe CAP to start the SSB transmission from time t+L1*N (N is a naturalnumber).

Referring to FIG. 21 , in an example according to various embodiments ofthe present disclosure, L2=8 TUs, L=4, L′=3, and L1=1 TU.

(a) indicates that L=4

(b) is an example in which for L′=3, an SSB burst set is transmittedfrom the starting time of L2, TU #0,

(c) is an example in which when a CAP for the transmission starting inTU #0 is failed, the SSB burst set is transmitted from the nextoccasion, TU #1 (TU #0+L1) after the CAP is successful. That is,according to various embodiments of the present disclosure, when the BSfails in the CAP for the transmission of the SSB burst set, which startsin TU #0, the BS may transmit the SSB burst set after succeeding in theCAP in the next occasion, TU #1.

(d) is an example in which when the CAPs for transmissions starting inTU #0 and TU #1 are failed, the SSB burst set is transmitted from thenext occasion, TU #2 (TU #1+L1) after the CAP is successful. That is,according to various embodiments of the present disclosure, when the BSfails in the CAP for the transmission of the SSB burst set, which startsin TU #0 and fails again in the CAP in the next occasion TU #0, the BSmay transmit the SSB burst set after succeeding in the CAP in the nextoccasion, TU #2.

(e) is an example in which when CAPs for transmissions starting in TU#0, TU #1, TU #2, TU #3, TU #4, TU #5, and TU #6 are failed, the SSBburst set is transmitted from the next occasion, TU #7 after a CAP issuccessful. That is, according to various embodiments of the presentdisclosure, when the BS fails in the CAPs for the transmissions of theSSB burst set, which start in TU #0, TU #1, TU #2, TU #3, TU #4, TU #5,and TU #6, the BS may transmit the SSB burst set after succeeding in aCAP in the next occasion, TU #7.

According to an exemplary embodiment, when an SSB burst transmissionstarts in TU #7, some SSB may be transmitted outside the L2 window, asin the example of (e). In an exemplary embodiment, when an SSB bursttransmission starts in a specific occasion within the L2 window and someSSB may be transmitted outside the L2 window as in the example of (e),the SSB may be transmitted in a corresponding occasion according to thefollowing Method 1 to Method 3.

Method 1

Once the SSB burst transmission starts in a corresponding occasion,transmission of the L′ SSBs may be allowed (even outside the L2 window).In the example of (e), although SSB #2 is outside the L2 window, SSB #0,SSB #1, and SSB #2 may be continuously transmitted.

Method 2

When the SSB burst transmission starts in the corresponding occasion andbecomes outside the L2 window, the SSB burst transmission may not beallowed to start in the occasion. In the example of (e), since SSB #2 isoutside the L2 window, the SSB burst transmission illustrated in (e) maynot be allowed. In this case, the SSB burst transmission illustrated in(e) may be dropped.

Method 3

When the SSB burst transmission starts in the corresponding occasion andbecomes outside the L2 window, the SSB burst transmission may be allowedto start in the occasion, while transmission of an SSB outside the L2window is not allowed. In the example of (e), the transmission of SSB #2may not be allowed. In this case, only SSB #0 and SSB #1 may betransmitted, while the transmission of SSB #2 is dropped, in the SSBburst illustrated in (e).

FIG. 22 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure.Particularly, L1=L in the illustrated case of FIG. 22 .

(a) indicates that L=4

(b) is an example in which for L′=3, an SSB burst set is transmittedfrom the starting time of L2, TU #0,

(c) is an example in which when a CAP for transmission of an SSB burstset starting in TU #0 is failed, the SSB burst set is transmitted fromthe next occasion, TU #2 (TU #0+L1) after a CAP is successful.

(d) is an example in which when the CAPs for the SSB burst settransmissions starting in TU #0 and TU #2 are failed, the SSB burst setis transmitted from the next occasion, TU #4 after a CAP is successful.

(e) is an example in which when the CAPs for the SSB burst settransmissions starting in TU #0, TU #2, and TU #4 are failed, the SSBburst set is transmitted from the next occasion, TU #6 after a CAP issuccessful.

According to various embodiments of the present disclosure, a method ofeliminating ambiguity that a UE receiving an SSB suffers from may beprovided. For example, on the assumption of L1<the transmission durationof L SSBs or L1<the transmission duration of L′ SSBs, the UE receivingSSBs may suffer from ambiguity about which SSB is transmitted in aspecific SSB occasion.

For example, referring to FIGS. 21(b) and 21(c), an SSB transmittable atthe beginning of TU #1 may be SSB #0 or SSB #2, which may depend on atime when a CAP is successful. The UE receiving SSBs does not haveknowledge of the success time of the CAP. Accordingly, even though theUE detects an SSB (particularly, a PSS/SSS) at the correspondingposition, the UE should identify whether the SSB is SSB #0 or SSB #2.According to various embodiments of the present disclosure describedbelow, methods of solving this problem may be provided.

3.1.2. <Option 2. Cyclically Rotated SSB Transmission

In option 2, for convenience, a minimum allowed time interval betweentransmissions of the same SSB is defined as L1. L1 may be represented intime units such as the number of slot and/or msec.

In various embodiments of the present disclosure, the same SSBs or thesame SSB indexes may be SSBs that the BS has transmitted using the sametransmission (TX) beam filter. Alternatively, in various embodiments ofthe present disclosure, the same SSBs or the same SSB indexes may beSSBs carrying fully or partially identical information. Alternatively,in various embodiments of the present disclosure, the same SSBs or thesame SSB indexes may be SSBs that the UE receives using the samereception (RX) beam filter.

In summary, in various embodiments of the present disclosure, the sameSSBs or the same SSB indexes may be interpreted as the same beams or thesame beam indexes, or may be interpreted as SSBs in a QCL relationship.

According to various embodiments of the present disclosure, the value ofL1 and/or L2 may be predefined. Alternatively, according to variousembodiments of the present disclosure, the value of L1 and/or L2 may beset by a UE-specific signal, a cell-specific signal, an L1 signal, or aMAC signal.

According to various embodiments of the present disclosure, the timeinterval L1 may be equal to or greater than the time duration of atleast L′ or L SSBs. According to various embodiments of the presentdisclosure, the BS may perform (attempt) a CAP for each SSB. Accordingto various embodiments of the present disclosure, a minimum SSB intervalat which a CAP may be attempted may be defined.

For example, when the BS fails in a first CAP, the BS may attempt asecond CAP after G SSBs. In an exemplary embodiment, G may be an integerequal to or greater than 1, which may be predefined. Alternatively, onlycandidate values for G may be predefined, and the BS may select a valuefor G from among the predefined candidates. In an exemplary embodiment,a rule for selecting a value for G from among predefined candidates maybe predefined.

Specifically, according to various embodiments of the presentdisclosure, with transmission occasions for SSBs configured within an L2window according to the value of L1, the BS may transmit an SSB burstset including L′ SSBs from a time when a CAP is actually successful.

FIG. 23 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure.

Referring to FIG. 23 , in an example according to various embodiments ofthe present disclosure, L2=8 TUs, L=4, L′=3, and L1=1.5 TU (i.e., thetransmission duration of L′ SSBs).

(a) indicates that L=4

(b) is an example in which for L′=3, an SSB burst set is transmittedfrom the starting time of L2, TU #0. (b) indicates candidate positionsat which SSBs may be located at L1 intervals.

(c) is an example in which when a CAP for the SSB burst set transmissionat the beginning of TU #0 is failed, the SSB burst set is transmittedfrom the next candidate, the middle of TU #0 after a CAP is successful.

(d) is an example in which the SSB burst set is transmitted from TU #1after a CAP is successful.

(e) is an example in which the SSB burst set is transmitted from themiddle of TU #6 after a CAP is successful.

(f) is an example in which the SSB burst set is transmitted from TU #7after a CAP is successful.

When the SSB burst set transmission as illustrated in the example of (e)is allowed, the number of candidates for SSB #0 is 6, and the number ofcandidates for each of SSB #1 and SSB #2 is 5. Therefore, the number orprobability of possible transmissions may vary for each SSB. In thisregard, according to various embodiments of the present disclosure, thenumber of candidates available for an SSB transmission within the L2window may be set equally for each of L′ SSBs.

For example, in FIG. 23 , SSB #0 allocated to the latter half of TU #7may be excluded so that the number of candidates for each SSB is equal.In this case, when an SSB burst set is transmitted from the middle of TU#6 after CAP success, only SSB #1 and SSB #2 are sequentiallytransmitted as in the example of (e). According to various embodimentsof the present disclosure, this transmission may not be allowed. Thatis, according to various embodiments of the present disclosure, onlywhen transmission of the L′ SSBs is guaranteed, transmission of the SSBburst set may be allowed to start. This may also be applied to a case inwhich L1>=the transmission duration of L SSBs (L1 is equal to or greaterthan L).

As in the example of (e), when the SSB burst transmission starts in TU#7, some SSB may be transmitted outside the L2 window. According tovarious embodiments of the present disclosure, when an SSB transmissionstarts in a specific occasion within the L2 window and some SSB may betransmitted outside the L2 window as in the example of (e), a method oftransmitting SSBs in a corresponding occasion may be provided.Specifically, the methods according to various embodiments of thepresent disclosure provided in Option. 1 may also be applied herein.

FIG. 24 is a diagram illustrating an exemplary SSB transmissionstructure according to various embodiments of the present disclosure.Particularly, L1=L in FIG. 24 .

(a) indicates that L=4.

(b) is an example in which for L′=3, an SSB burst set is transmittedfrom the starting time of L2, TU #0. (b) indicates candidate positionsat which each SSB may be located at L1 intervals.

(c) is an example in which when a CAP for the SSB burst set transmissionat the beginning of TU #0 is failed, the SSB burst set is transmittedfrom the next occasion, the middle of TU #0 after a successful CAP.

d) is an example in which the SSB burst set is transmitted from TU #1after a successful CAP.

(e) is an example in which the SSB burst set is transmitted from themiddle of TU #6 after a successful CAP.

(f) is an example in which the SSB burst set is transmitted from TU #7after a successful CAP.

In the example of (b), according to various embodiments of the presentdisclosure, ‘X’ may be filled with any DL signal or channel by the BS.Alternatively, according to various embodiments of the presentdisclosure, ‘X’ may be filled with a predefined DL signal or channel.Alternatively, according to various embodiments of the presentdisclosure, the BS may not fill ‘X’ with any DL signal or channel.According to various embodiments of the present disclosure, when ‘X’ isnot filled with any DL signal or channel, the BS may additionallyattempt a CAP, and transmit SSB #n from the success time of the CAP.

As in the example of (f), when the SSB burst set transmission starts inTU #7, some SSB may be transmitted outside the L2 window. According tovarious embodiments of the present disclosure, when an SSB transmissionstarts in a specific occasion within the L2 window and some SSB may betransmitted outside the L2 window as in the example of (f), a method oftransmitting SSBs in a corresponding occasion may be provided. In anexemplary embodiment, the methods according to various embodiments ofthe present disclosure provided in Option. 1 may also be applied herein.According to various embodiments of the present disclosure, whentransmission of SSB #0 is not allowed, transmission in ‘X’ may not beperformed either.

As illustrated in FIG. 24 , when L1>the transmission duration of L′ SSBs(i.e., L1 exceeds L′), a transmission period such as ‘X’ may berequired. According to various embodiments of the present disclosure, aspecific SSB may be transmitted during a transmission period such as‘X’. In the example of FIG. 24 , one of SSB #0, SSB #1, and SSB #2 maybe transmitted in the transmission period ‘X’. According to variousembodiments of the present disclosure, a rule for determining an SSB tobe transmitted in the transmission period ‘X’ may be defined.

In an exemplary embodiment, an SSB to be transmitted during thetransmission period ‘X’ may be predefined according to a specific rule.

In an exemplary embodiment, the specific rule may be a function of SSB#0 or a function of a cell ID. Alternatively, an SSB to be transmittedduring the transmission period ‘X’ may be configured by a UE-specific orcell-specific signal (e.g., an RRC signal, an L1 signal, or a MACsignal).

In an exemplary embodiment, the BS may operate in a stand-alone (SA)cell (e.g., a primary cell (PCell)) in the unlicensed band.Alternatively in an exemplary embodiment, the BS may operate in anon-stand-alone (NSA) cell (e.g., a primary secondary cell (PSCell) orsecondary cell (SCell)).

According to various embodiments of the present disclosure, the value ofL1 and/or the number of SSBs related to L1 may be configured for orindicated to the UE by a cell-specific RRC signal or a UE-specific RRCsignal. In an exemplary embodiment, the cell-specific RRC signal may be,but not limited to, a PBCH, remaining minimum system information (RMSI),other system information (OSI), or the like.

In an exemplary embodiment, when the BS operates in an SA cell inOption. 1 and Option. 2, only the transmission duration of L1=L SSBs maybe allowed.

When L1≠L (L1 is not the transmission duration of L SSBs) or when L1<L(L1 is the transmission duration of fewer SSBs than L), time-axispositions at which the same SSB is transmittable may be changedaccording to the value of L1 and the number of SSBs related to L1.Therefore, the BS needs to indicate the value of L1 and/or the number ofSSBs related to L1 to the UE. In an exemplary embodiment, the BS maysignal the value of L1 and/or the number of SSBs related to L1 to the UEby PBCH payload.

To guarantee the transmission reliability of a PBCH, PBCH payload needsto be minimized. Therefore, compressing the above information as much aspossible and loading the compressed information in the PBCH payload maybe favorable. For this purpose, according to various embodiments of thepresent disclosure, the BS may indicate an SSB ending index or thenumber of SSBs to the UE.

Specifically, according to various embodiments of the presentdisclosure, the BS may indicate the SSB ending index or the number ofSSBs to the UE by the PBCH payload. According to various embodiments ofthe present disclosure, the UE may assume that SSBs with consecutiveindexes from SSB index 0 to the SSB ending index or as many consecutiveindexes from SSB index 0 as the number of SSBs signaled from the BS aretransmitted.

According to various embodiments of the present disclosure, the intervalbetween SSBs may be signaled to the UE by the PBCH payload. Although anSSB should be transmitted in every half-slot in the above-describedexamples, the BS may transmit only one SSB in a specific slot, andmultiplex RMSI, a CSI-RS, and so on in the remaining resource area ofthe slot. In this case, it may be necessary to transmit the SSB in everyslot, not in every half-slot.

According to various embodiments of the present disclosure, in thisregard, the BS may signal the interval between SSBs to the UE by thePBCH payload. According to various embodiments of the presentdisclosure, one bit may be added to the PBCH payload to indicate whetherthe interval between SSBs is a half-slot according to the value of thebit. In an exemplary embodiment, one bit may be added to the PBCHpayload to indicate to the UE that the interval between SSBs is ahalf-slot, when the one bit is set to ‘0’ (or ‘1’). According to variousembodiments of the present disclosure, it may be generalized that theinterval between SSBs or the transmission periodicity of one SSB may betransmitted to the UE by PBCH payload or cell-specific or UE-specificRRC signaling.

According to various embodiments of the present disclosure, the intervalbetween SSBs (or the transmission periodicity of one SSB) and an SSBending index (or the number of SSBs) may be jointly signaled. That is,according to various embodiments of the present disclosure, informationabout the interval between SSBs or the transmission periodicity of oneSSB and information about an SSB ending index or the number of SSBs maybe jointly transmitted to the UE. For example, according to variousembodiments of the present disclosure, one bit may be added to the PBCHpayload, and when the bit is set to ‘0’ (or ‘1’), this may indicate tothe UE that the interval between SSBs is a half-slot (or two SSBs aretransmitted in one slot). Alternatively, according to variousembodiments of the present disclosure, if the bit is set to ‘1’ (or‘0’), this may indicate to the UE that the interval between SSBs is aslot (or one SSB is transmitted in one slot). According to variousembodiments of the present disclosure, when the signaled number of SSBsis 2 and the interval between SSBs is a half-slot, this may imply thatSSB #0 and SSB #1 may be transmitted in one slot. Further, according tovarious embodiments of the present disclosure, when the signaled numberof SSBs is 2 and the interval between SSBs is a slot, SSB #0 maytransmitted in one slot (without SSB #1 in the slot), and then SSB #2(or SSB #1) may be transmitted in the next one slot.

While various embodiments of the present disclosure have been describedabove in the context of the PBCH by way of example, the method ofindicating an SSB transmission pattern such as a transmission SSBindex/the number of SSBs or the transmission periodicity of an SSBaccording to various embodiments of the present disclosure describedabove may also be applied to RRC signaling other than the PBCH. That is,those skilled in the art will clearly understand that a PBCH may bereplaced with other RRC signaling in the method of indicating atransmission SSB index/the number of SSBs or the transmissionperiodicity of an SSB according to the various embodiments of thepresent disclosure described above. According to various embodiments ofthe present disclosure, when the interval between SSBs is a slot, thismay mean that a timing synchronization relationship between a servingcell and a neighboring cell may differ by about 1 slot at maximum.

RRC signaling other than the PBCH may have more margin in terms ofpayload than the PBCH. In this regard, according to various embodimentsof the present disclosure, when the SSB transmission pattern of acorresponding cell or a cell in a different frequency is indicated byRRC signaling (other than the PBCH), a method other than theabove-described method may be applied.

In an exemplary embodiment, an L-bit bitmap and a repetition number maybe signaled. For example, when “bitmap of 1000+repetition number 1” issignaled for L=4, only SSB #0 may be transmitted, and the value of L1 orthe number of SSBs may be 1 in the above-described Option. 2. That is,in an exemplary embodiment, because L=4, SSB #0, SSB #1, SSB #2, and SSB#3 may be transmitted. Due to the bitmap of 1000, only SSB #0 istransmitted. Alternatively, when “bitmap of 1000+repetition number 2” issignaled for L=4, only SSB #0 may be transmitted, and the number of SSBsrelated to L1 may be 2 in Option. 2 (i.e., although SSB #1 is nottransmitted, no SSB is transmitted in the corresponding resources).

When a plurality of candidate positions are available for transmissionof one SSB in Option. 1 and Option. 2, an actual transmission positionamong the candidate positions may be signaled according to variousembodiments of the present disclosure. Information about the actualtransmission position may be jointly encoded with the value of L1 and/orthe number of SSBs related to L1 according to various embodiments of thepresent disclosure. In an exemplary embodiment, the information aboutthe actual transmission position among the candidate positions may beloaded in PBCH payload and jointly encoded with the value of L1 and/orthe number of SSBs related to L1.

For convenience, let the maximum number of candidate positions availablefor transmission of an SSB within an L2 window be denoted by Y. In anexemplary embodiment, when the value of L1 and/or the number of SSBsrelated to L1 is 1, the number of candidate positions available fortransmission of SSB #0 may be Y. In an exemplary embodiment, when thevalue of L1 and/or the number of SSBs related to L1 is 2, the number ofcandidate positions available for transmission of SSB #0 may be Y/2. Inan exemplary embodiment, when Y/2 is not an integer, Y/2 may besubjected to ceiling or flooring.

In summary, the number of bits required to indicate the value of L1and/or the number of SSBs related to L1, and a resulting actualtransmission position for each SSB may be determined by the followingequation according to various embodiments of the present disclosure.

$\begin{matrix}{n_{bit} = {{ceiling}\left( {\log_{2}{\sum_{n = 1}^{L}{{flooring}\left( \frac{Y}{n} \right)}}} \right)}} & \lbrack{Equation}\rbrack\end{matrix}$

In the equation, n_(bit) is the number of bits required to indicate thevalue of L1 and/or the number of SSBs related to L1, and a resultingactual transmission position for each SSB. L is the maximum number ofSSBs transmittable from the BS. Y is the maximum number of candidatepositions available for transmission of an SSB within an L2 window. Inthe equation, ceiling and flooring may be exchanged with each other.

As described above, the value of L1 and/or the number of SSBs related toL1 may be configured for or indicated to the UE by cell-specific RRCsignaling or UE-specific RRC signaling. As described above, according tovarious embodiments of the present disclosure, the cell-specific RRCsignaling may be, but not limited to, a PBCH, RMSI, or OSI.

According to various embodiments of the present disclosure, which one of(predetermined) limited values is the value of L1 and/or the number ofSSBs related to L1 may be configured for or indicated to the UE bycell-specific RRC signaling or UE-specific RRC signaling. In otherwords, according to various embodiments of the present disclosure,values available as the value of L1 and/or the number of SSBs related toL1 may be predefined, and a specific one of the predefined values may beconfigured for or indicated to the UE by cell-specific RRC signaling orUE-specific RRC signaling.

In an exemplary embodiment, the value of L1 may be limited to 4 or 8.The BS may signal the value of L1 as 4 or 8 to the UE by one bit of acell-specific RRC signal or a UE-specific RRC signal.

In an exemplary embodiment, the value of L1 may be limited to an evennumber (2, 4, 6, or 8). The B S may signal the value of L1 as 2, 4, 6,or 8 to the UE by two bits of the cell-specific RRC signal or aUE-specific RRC signal.

In an exemplary embodiment, the value of L1 may be limited to thefactors of 8 (1, 2, 4, or 8). The B S may signal the value of L1 as 1,2, 4, or 8 to the UE by two bits of the cell-specific RRC signal or aUE-specific RRC signal.

It may be generalized that values available as L1 are predefined, and acertain set of a plurality of candidate values for L1 is configuredaccording to various embodiments of the present disclosure. The BS mayindicate a specific one of the plurality of candidate values to the UEby a cell-specific RRC signal or a UE-specific RRC signal. According tovarious embodiments of the present disclosure, the specific one of theplurality of candidate values may be indicated by bits in thecell-specific RRC signal or the UE-specific RRC signal, and the numberof the bits may be equal to the number of the plurality of candidatevalues in the certain set.

3.1.3. Method of Determining Value of L

In the NR system, the value of L may be predefined or preconfiguredband-specifically. For example, L=4 at 3 GHz or below, L=8 at 6 GHz orbelow, and L=64 at 6 GHz or above.

According to various embodiments of the present disclosure, a differentL value may be set in an NR system supporting an unlicensed bandoperating in a sub-7 GHz band. For example, according to variousembodiments of the present disclosure, the value of L may be set basedon the following options. Those skilled in the art will clearlyunderstand that the value of L may be set based on a combination of allor some of the following options, unless contradicting each other.

Opt. 1: Method of defining value of L for transmission during Y msec

For example, Y=1.

For example, when Y=1, L=2 for a 15-kHz SCS according to variousembodiments of the present disclosure.

For example, when Y=1, L=4 for a 30-kHz SCS according to variousembodiments of the present disclosure.

For example, when Y=1, L=8 for a 60-kHz SCS according to variousembodiments of the present disclosure.

Opt. 2: Method of defining different value of L according to SCS

In an exemplary embodiment, L=2 for the 15-kHz SCS.

In an exemplary embodiment, L=4 for the 30-kHz SCS.

In an exemplary embodiment, L=8 for the 60-kHz SCS.

Opt. 3: Method of defining different value of L according to (sub)bandin sub-7 GHz band

In an exemplary embodiment, L=2 at 5150 to 5250 MHz.

In an exemplary embodiment, L=4 at 5250 to 5350 MHz.

According to various embodiments of the present disclosure, the value ofL used in the NR system may be maintained, while the maximum value of L1(i.e., the number of SSBs actually transmitted by the BS, equal to orless than L) may be limited. According to various embodiments of thepresent disclosure, L may be replaced with the maximum value of L′ inOpt. 1 to Opt. 3.

If an SS/PBCH block (or a part of the SS/PBCH block, for example, a PSS)should be transmitted repeatedly even within one L2 window, therepetition number needs to be associated with L (and/or L′). Forexample, when an SS/PBCH block (or a part of the SS/PBCH block, forexample, a PSS) should be transmitted X times repeatedly within one L2window, L (and/or L′) may be restricted to a multiple of X.

3.1.3.1 Method of Setting Different Value of L According to BS Operation(SA/NSA)

According to various embodiments of the present disclosure, the BS mayoperate in an SA cell (e.g., a PCell) in the unlicensed band.Alternatively, according to various embodiments of the presentdisclosure, the BS may operate in an NSA cell (e.g., a PSCell or SCell).

According to various embodiments of the present disclosure, differentvalues of L (and/or different maximum values of L′) may be defined forBS operations in an SA cell and an NSA cell.

For example, according to various embodiments of the present disclosure,when the BS operates in an SA cell, the value of L (or the maximum valueof L′) may be defined as 4.

For example, according to various embodiments of the present disclosure,when the BS operates in an NSA cell, the value of L (or the maximumvalue of L′) may be defined as 8.

3.1.4. Method of Configuring Interval Between SSBs

FIGS. 25 and 26 are diagrams illustrating exemplary SSB transmissionstructures according to various embodiments of the present disclosure.

Referring to FIG. 25 , for the 15-kHz SCS and the 30-kHz SCS, SSBtransmission symbols may be determined in the NR system, as illustratedin FIG. 25 . That is, in an exemplary embodiment, for the 15-kHz SCS,one SSB may be transmitted in symbols #2, #3, #4, and #5 in a slot, andanother SSB may be transmitted in symbols #8, #9, #10, and #11 in thesame slot.

In an exemplary embodiment, there may be two patterns for the 30-kHzSCS. In the first pattern (30 kHz SCS (1)), for example, SSB #n may betransmitted in symbols #2 and #3 in a slot, SSB #n+1 may be transmittedin symbols #4 and #5 in the same slot, SSB #n+2 may be transmitted insymbols #8 and #9 in the same slot, and SSB #n+3 may be transmitted insymbols #10 and #11 in the same slot.

In the second pattern (30 kHz SCS (2)), for example, SSB #n may betransmitted in symbols #1 and #2 in a slot, SSB #n+1 may be transmittedin symbols #4 and #5 in the same slot, SSB #n+2 may be transmitted insymbols #8 and #9 in the same slot, and SSB #n+3 may be transmitted insymbols #11 and #12 in the same slot.

The interval between SSB #n and SSB #n+1 is defined as Interval #n, andthe interval between SSB #n+1 and SSB #n+2 is defined as Interval #n+1.It may be noted that Interval #n is different from Interval #n+1.

For example, Interval #n may be 2 symbols and Interval #n+1 may be 4symbols in the cases of the 15-kHz SCS and the second pattern (30 kHzSCS (2)). In the case of the first pattern (30 kHz SCS (1)), Interval #nmay be 0 symbol and Interval #n+1 may be 4 symbols.

However, because signal transmission or non-transmission depends on aCAP result in the unlicensed band, a specific SSB transmission at apredetermined timing may not be guaranteed. That is, considering thatthe transmission position of an SSB is variable according to a CAPresult in the unlicensed band, when a UE which has detected a specificSBS attempts the next SSB detection, an inconsistent interval betweenSSBs may lead to ambiguity about the transmission timing of the nextSSB.

To avert the above problem, various embodiments of the presentdisclosure may provide a method of maintaining the interval between SSBsto be constant.

For example, referring to FIG. 26 , the interval between SSBs may be 3symbols consistently according to various embodiments of the presentdisclosure. Obviously, FIG. 26 is exemplary. According to variousembodiments of the present disclosure, SSB #n may be transmitted insymbols #3, #4, #5, and #6 (or #0, #1, #2, and #3 or #1, #2, #3, and#4), and SSB #n+1 may be transmitted 3 symbols later.

3.2. From Perspective of Cell Acquisition

In the NR system, when the UE successfully receives an SSB, the UE mayobtain system frame number (SFN) information, frame boundaryinformation, and slot boundary information. Subsequently, the UE mayreceive a PDCCH/PDSCH for system information from the BS. However,because signal transmission or non-transmission in the unlicensed banddepends on a CAP result, a specific SSB transmission at a predeterminedtiming may not be guaranteed as described in subclause 3.1. Accordingly,the UE may have difficulty in obtaining the SFN information, the frameboundary information, and the slot index/boundary information.

According to various embodiments of the present disclosure describedbelow, a method of enabling a UE to obtain SFN information, frameboundary information, and slot boundary information may be provided toovercome the above problem. Various embodiments of the presentdisclosure may also be applied, when the UE obtains timing informationabout a cell to be measured during neighboring cell measurement and/orintra-frequency measurement and/or inter-frequency measurement. Thiswill be easily understood to those skilled in the art.

3.2.1. [Method #1] Acquisition of Frame/Slot Boundary/Index Informationfrom PBCH Payload

According to various embodiments of the present disclosure, method #1 ofenabling a UE to obtain frame/slot boundary/index information from PBCHpayload may be provided. Method #1 may be effective, particularly whenPBCH decoding is possible in one slot, that is, PBCH decoding ispossible even with one SSB reception.

According to various embodiments of the present disclosure, frame/slotboundary/index information may be fully and/or partially transmitted tothe UE by a PBCH scrambling sequence. According to various embodimentsof the present disclosure, the frame/slot boundary/index information maybe fully and/or partially transmitted to the UE by a DL signal/channel(e.g., system information) multiplexed with an SSB.

Referring to FIGS. 21 and 23 , for convenience, it is assumed thatL1<{transmission duration of L (or L′) SSBs} in Option. 1 or the valueof L1 is a function of the transmission duration L′ in Option. 2according to various embodiments of the present disclosure describedbefore in subclause 3.1.

According to various embodiments of the present disclosure, PBCHdemodulation reference signal (DM-RS) sequence information may be linkedto SSB #0, SSB #1, and SSB #2 as illustrated in FIGS. 21 and 23 .According to various embodiments of the present disclosure, the PBCHDM-RS sequence may be the same regardless of a TU actually carrying SSB#0(½) in an L2 window. That is, according to various embodiments of thepresent disclosure, the same PBCH DM-RS sequence may be configuredirrespective of (with no regard to) a TU carrying SSB #0(½) within L2.

According to various embodiments of the present disclosure, upondetection of a PSS/SSS, the UE may identify whether a PBCH DM-RSsequence corresponds to SSB #0, SSB #1, SSB #2, or SSB #3 by blinddetection (BD). According to various embodiments of the presentdisclosure, because the BS may transmit up to L SSBs, the UE may assumethat L SSBs may be transmitted until obtaining information about L′. Forexample, because L=4 in the example of FIG. 21 or FIG. 23 , the UE mayassume that SSB #0, SSB #1, SSB #2, and SSB #3 may be transmitted.

According to various embodiments of the present disclosure, the UE maydecode the PBCH based on the detected PBCH DM-RS and thus obtain frameand/or slot boundary and/or index information from PBCH payload and/or aPBCH scrambling sequence.

According to various embodiments of the present disclosure, thetime-domain size of the L2 window may be set equally regardless of theSCS of an SSB or an SS/PBCH block. In this case, according to variousembodiments of the present disclosure, as the SSB or SS/PBCH block has alarger SCS, more SSBs or SS/PBCH blocks may be transmitted within the L2window. In an exemplary embodiment, the number of SSBs or SS/PBCH blockstransmittable within the L2 window may be proportional to the SCS.

In an exemplary embodiment, when the SCS of an SSB or SS/PBCH block is15 kHz, N SSBs or SS/PBCH blocks may be transmittable within the L2window. In this case, according to various embodiments of the presentdisclosure, when the SCS of an SSB or SS/PBCH block is 30 kHz, 2N SSBsor SS/PBCH blocks may be transmittable within the L2 window.

Therefore, according to various embodiments of the present disclosure,as the SCS of an SSB or SS/PBCH block increases, a larger amount of PBCHinformation may be needed to indicate frame and/or slot boundary/indexinformation to the UE. In an exemplary embodiment, the required amountof PBCH information may be proportional to the SCS.

In an exemplary embodiment, when the SCS of an SSB or SS/PBCH block is15 kHz, frame and/or slot boundary/index information may be indicated tothe UE by 1-bit PBCH payload. In an exemplary embodiment, when the SCSof an SSB or SS/PBCH block is 30 kHz, frame and/or slot boundary/indexinformation may be indicated to the UE by 2-bit PBCH payload.

That is, according to various embodiments of the present disclosure,when the SCS of an SSB or SS/PBCH block is 15 kHz, the UE may obtainframe and/or slot boundary/index information based on 1-bit PBCHpayload. In this case, according to various embodiments of the presentdisclosure, when the SCS of an SSB or SS/PBCH block is 30 kHz, the UEmay obtain frame and/or slot boundary/index information based on 2-bitPBCH payload.

3.2.2. [Method #2] Acquisition of Frame/Slot Boundary/Index Informationfrom DM-RS Sequence of PDCCH (and PDSCH) Multiplexed with SSB

According to various embodiments of the present disclosure, the UE mayobtain frame/slot boundary/index information from the DM-RS sequence ofa PDCCH (and a PDSCH) multiplexed with an SSB in method #2.

Referring to FIGS. 21 and 23 , for convenience, it is assumed thatL1<{the transmission duration of L (or L′) SSBs} in Option. 1 or thevalue of L1 is a function of the transmission duration L′ in Option. 2according to various embodiments of the present disclosure describedbefore in subclause 3.1. According to various embodiments of the presentdisclosure, PBCH DM-RS sequence information may be linked to SSB #0, SSB#1, and SSB #2 as illustrated in FIGS. 21 and 23 .

According to various embodiments of the present disclosure, PBCH payloadand a PBCH scrambling sequence as well as a PBCH DM-RS sequence may bethe same regardless of a TU actually carrying SSB #0(½) in an L2 window.That is, according to various embodiments of the present disclosure, thesame PBCH DM-RS sequence, the same PBCH payload, and the same PBCHscrambling sequence may be configured irrespective of (with no regardto) a TU carrying SSB #0(½) within L2.

For convenience, the period of an L2 window is K [msec]. According tovarious embodiments of the present disclosure, although the UE detects aDM-RS sequence corresponding to SSB #0 by blind-detecting a PBCH DM-RSwithin the L2 window and then attempts PBCH decoding, a CRS error mayoccur in some cases. In this case, according to various embodiments ofthe present disclosure, when the UE detects the DM-RS sequencecorresponding to SSB #0 by performing blind detection on the PBCH DM-RSin an L2 window before or after the L2 window in which the UE has failedin PBCH decoding, the UE may attempt PBCH combining.

That is, according to various embodiments of the present disclosure,upon detection of a DM-RS sequence corresponding to SSB #0 by performingblind detection on a PBCH DM-RS in an L2 window before or after an L2window in which the UE has failed in PBCH decoding, the UE may attemptPBCH combining. According to various embodiments of the presentdisclosure, various methods are available for PBCH combining. Forexample, a PBCH combining scheme used in the NR system may be used.

According to various embodiments of the present disclosure, even thoughthe UE has succeeded in PBCH decoding, the UE may not have obtainedaccurate slot boundary information and/or slot index information. Thisis because even though the UE detects SSB #0 in TU #0 in the first L2window and detects TU #2 in the L2 window after K [msec], the UE is notcapable of distinguishing them from the cases of TU #2 (in the first L2window) and TU #4 (in the next L2 window), respectively. That is, eventhough SSB #0 is detected in TU #0 in the first L2 window and TU #2 isdetected in the next L2 window after K [msec], the UE may notdistinguish TU #0 and TU #2 from TU #2 in the first L2 window and TU #4in the next L2 window, respectively.

Therefore, according to various embodiments of the present disclosure,the UE may obtain slot (and frame) index/boundary information bydetecting SSB #0 in an L2 window after another K [msec] andblind-detecting the DM-RS sequence of a PDCCH scheduled or configuredwithin a corresponding TU.

In an exemplary embodiment, the DM-RS sequence of the scheduled orconfigured PDCCH may be a function of a slot and/or symbol index.

According to various embodiments of the present disclosure, thetime-domain size of an L2 window may be equally set regardless of theSCS of an SSB or SS/PBCH block. In this case, according to variousembodiments of the present disclosure, as the SSB or SS/PBCH block has alarger SCS, more SSBs or SS/PBCH blocks may be transmitted within the L2window.

In an exemplary embodiment, the number of SSBs or SS/PBCH blockstransmittable within the L2 window may be proportional to the SCS.

In an exemplary embodiment, when the SCS of an SSB or SS/PBCH block is15 kHz, N SSBs or SS/PBCH blocks may be transmittable within the L2window. In this case, according to various embodiments of the presentdisclosure, when the SCS of an SSB or SS/PBCH block is 30 kHz, 2N SSBsor SS/PBCH blocks may be transmittable within the L2 window.

Accordingly, according to various embodiments of the present disclosure,as the SCS of an SSB or SS/PBCH block increases, a larger number ofDM-RS sequences may be needed to indicate frame and/or slotboundary/index information to the UE. In an exemplary embodiment, therequired number of DM-RS sequences may be proportional to the SCS.

3.2.3. [Method #3] Acquisition of Slot Boundary/Index Information fromPBCH DM-RS

According to various embodiments of the present disclosure, the UE mayobtain slot boundary and/or index information from a PBCH DM-RS inmethod #3.

Referring to FIGS. 22 and 24 , for convenience, it is assumed thatL1>={transmission duration of L SSs} in Option. 1 or the value of L1 isnot related to the transmission duration L′ in Option. 2 according tovarious embodiments of the present disclosure described before insubclause 3.1. According to various embodiments of the presentdisclosure, a PBCH DM-RS sequence may be different depending on a TUcarrying the PBCH DM-RS despite the same SSB #0, SSB #1, or SSB #2.

In an exemplary embodiment, a different PBCH DM-RS sequence may bedefined depending on a TU carrying the PBCH DM-RS sequence despite thesame SSB #0, SSB #1, or SSB #2.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #0transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#0, index #4, index #8, and index #12, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #1transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#1, index #5, index #9, and index #13, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #2transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#2, index #6, index #10,and index #14,respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #3transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#3, index #7, index #11, and index #15, respectively.

According to various embodiments of the present disclosure, afterPSS/SSS detection, the UE may obtain slot boundary and/or indexinformation by bind-detection of a PBCH DM-RS sequence. However, SFNinformation may not be obtained from the PBCH.

For example, it is assumed that L=4. In an exemplary embodiment, whenthe UE succeeds in detecting a sequence corresponding to PBCH DM-RSsequence index #8 in the first L2 window and succeeds in detecting asequence corresponding to PBCH DM-RS sequence index #4 in the L2 windowafter K [msec], the UE may identify that both SSBs are SSB #0. Further,according to various embodiments of the present disclosure, the UE mayobtain SFN information by combining PBCHs included in the two SSBs.

The above-described method may also be applied, when the value of L1 isa function of the transmission duration L′ (e.g., L1=L′), which may beclearly understood by those skilled in the art.

Referring to FIG. 23 , according to various embodiments of the presentdisclosure, a different PBCH DM-RS sequence may be defined depending ona TU carrying the PBCH DM-RS sequence despite the same SSB #0, SSB #1,or SSB #2.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #0transmitted in TU #0, TU #1, TU #3, TU #4, TU #6, and TU #7 maycorrespond to index #0, index #3, index #6, index #9, index #12,andindex #15,respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #1transmitted in TU #0, TU #2, TU #3, TU #5, and TU #6 may correspond toindex #1, index #4, index #7, index #10, and index #13, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #2transmitted in TU #1, TU #2, TU #4, TU #5, and TU #7 may correspond toindex #2, index #5, index #8, index #11, and index #14, respectively.

According to various embodiments of the present disclosure, afterPSS/SSS detection, the UE may obtain slot boundary and/or indexinformation by blind-detection of a PBCH DM-RS sequence. However, SFNinformation may not be obtained from the PBCH.

For example, it is assumed that the UE succeeds in detecting a sequencecorresponding to PBCH DM-RS sequence index #6 in the first L2 window,and then succeeds in detecting a sequence corresponding to PBCH DM-RSsequence index #3 in the L2 window after K [msec]. In an exemplaryembodiment, the UE may recognize that both SSBs are SSB #0 based on thefact that the result values of a modulo (mod) operation between theDM-RS sequence indexes and L1 are all equal to 0. In an exemplaryembodiment, the UE may obtain SFN information by combining PBCHsincluded in the two SSBs.

In the NR system, 3 least significant bits (LSBs) of a PBCH DM-RS indexmay be used as the second scrambling code of a PBCH. However, accordingto various embodiments of the present disclosure described above, SFNinformation may be obtained through PBCH combining by using log 2(L)LSBs of a PBCH DM-RS index as the second scrambling code.

For example, if L=4, the UE should use only log 2(L) LSBs of a PBCHDM-RS index, that is, 2 bits, as the second scrambling sequence toobtain SFN information through PBCH combining as in the NR system.

According to various embodiments of the present disclosure, thetime-domain size of an L2 window may be configured equally regardless ofthe SCS of an SSB or SS/PBCH block. In this case, according to variousembodiments of the present disclosure, as the SSB or SS/PBCH block has alarger SCS, more SSBs or SS/PBCH blocks may be transmitted within the L2window. In an exemplary embodiment, the number of SSBs or SS/PBCH blockstransmittable within the L2 window may be proportional to the SCS.

In an exemplary embodiment, when the SCS of an SSB or SS/PBCH block is15 kHz, N SSBs or SS/PBCH blocks may be transmittable within the L2window. In this case, according to various embodiments of the presentdisclosure, when the SCS of an SSB or SS/PBCH block is 30 kHz, 2N SSBsor SS/PBCH blocks may be transmittable within the L2 window.

Accordingly, according to various embodiments of the present disclosure,as the SCS of an SSB or SS/PBCH block increases, a larger number of PBCHDM-RS sequences may be needed to indicate frame and/or slotboundary/index information to the UE. In an exemplary embodiment, therequired number of PBCH DM-RS sequences may be proportional to the SCS.

In an exemplary embodiment, when the SCS of an SSB or SS/PBCH block is15 kHz, frame and/or slot boundary/index information may be indicated tothe UE based on N PBCH DM-RS sequences. In an exemplary embodiment, whenthe SCS of an SSB or SS/PBCH block is 30 kHz, frame and/or slotboundary/index information may be indicated to the UE based on 2N PBCHDM-RS sequences.

That is, according to various embodiments of the present disclosure,when the SCS of an SSB or SS/PBCH block is 15 kHz, the UE may obtainframe and/or slot boundary/index information based on N PBCH DM-RSsequences. In an exemplary embodiment, when the SCS of an SSB or SS/PBCHblock is 30 kHz, the UE may obtain frame and/or slot boundary/indexinformation based on 2N PBCH DM-RS sequences.

3.2.4. [Method #4] Acquisition of Slot Boundary/Index Information fromCombination of SSS (or PSS) and PBCH DM-RS

According to various embodiments of the present disclosure, method #4 inwhich the UE obtains slot boundary and/or index information from acombination of an SSS or PSS and a PBCH DM-RS may be provided.

Referring to FIGS. 22 and 24 , for convenience, it is assumed thatL1>={transmission duration of L SSBs} in Option. 1, or the value of L1is independent of the transmission duration L′ in Option. 2 according tovarious embodiments of the present disclosure, described in subclause3.1.

According to various embodiments of the present disclosure, acombination of an SSS (or PSS) and a PBCH DM-RS sequence may varydepending on which TU carries the combination despite the same SSB #0,SSB #1, or SSB #2.

That is, according to various embodiments of the present disclosure, adifferent combination of an SSS (or PSS) and a PBCH DM-RS sequence maybe defined according to a TU carrying the combination in spite of thesame SSB #0, SSB #1, or SSB #2.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #0transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#0, index #4, index #0, and index #4, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #1transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#1, index #5, index #1, and index #5, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #2transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#2, index #6, index #2, and index #6, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #3transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#3, index #7, index #3, and index #7, respectively.

In an exemplary embodiment, SSSs (or PSSs) corresponding to TU #0, TU#1, TU #2, and TU #3 may belong to SSS group A (or PSS group A).

In an exemplary embodiment, SSSs (or PSSs) corresponding to TU #4, TU#5, TU #6, and TU #7 may belong to SSS group B (or PSS group B).

In the NR system, SSSs with 336 sequences may be grouped, such that eachof SSS group A and SSS group B may include 168 sequences. According tovarious embodiments of the present disclosure, after PSS/SSS detection,the UE may obtain slot boundary and/or index information based on theSSS detection and blind-detection of a PBCH DM-RS sequence. However, SFNinformation may not be obtained from the PBCH.

In an exemplary embodiment, it is assumed that L=4. In an exemplaryembodiment, when the UE succeeds in detecting a sequence correspondingto PBCH DM-RS sequence index #0 and SSS group B in the first L2 windowand detecting a sequence corresponding to PBCH DM-RS sequence index #4and SSS group A the L2 window after K [msec], the UE may identify thatboth SSBs are SSB #0. In an exemplary embodiment, the UE may obtain SFNinformation by combining PBCHs included in the two SSBs. As describedabove, in the NR system, 3 LSBs of a PBCH DM-RS index may be used as thesecond scrambling code of the PBCH.

However, in various embodiments of the present disclosure describedabove, SFN information may be obtained through PBCH combining by usinglog 2(L) LSBs of the PBCH DM-RS index as the second scrambling code. Inthis example, since L=4, the UE should use only the log 2(L=4) LSBs ofthe PBCH DM-RS index, that is, 2 bits, as the second scrambling sequenceto obtain SFN information through PBCH combining.

3.2.5. [Method #5] Acquisition of Slot Boundary/Index Information fromCombination of Separate DL Signal and PBCH DM-RS

According to various embodiments of the present disclosure, method #4 inwhich the UE obtains slot boundary and/or index information based on acombination of a separate DL signal and a PBCH DM-RS may be provided.

According to various embodiments of the present disclosure, a separateDL signal may be defined. The defined DL signal may be multiplexed withan SSB. Similarly to method #4 of obtaining slot boundary and/or indexinformation according to various embodiments of the present disclosuredescribed above, the UE may combine the defined DL signal with PBCHDM-RS information to obtain slot boundary and/or index information.

According to various embodiments of the present disclosure, the REpositions of the DL signal multiplexed with the SSB may be predefined.Alternatively, according to various embodiments of the presentdisclosure, the RE positions of the DL signal multiplexed with the SSBmay be determined based on a function of a Cell-ID. That is, accordingto various embodiments of the present disclosure, the positions of theREs in a resource area, to which the DL signal multiplexed with the SSBis mapped, may be preset or predefined, or determined based on afunction of a cell ID.

Referring to FIGS. 22 and 24 , for convenience, it is assumed thatL1>={transmission duration of L SSBs} in Option. 1, or the value of L1is independent of the transmission duration L′ in Option. 2 according tovarious embodiments of the present disclosure, described in subclause3.1. According to various embodiments of the present disclosure, acombination of an SSS (or PSS) and a PBCH DM-RS sequence may varydepending on which TU carries the combination despite the same SSB #0,SSB #1, or SSB #2.

That is, according to various embodiments of the present disclosure, adifferent combination of an SSS (or PSS) and a PBCH DM-RS sequence isdefined according to a TU carrying the combination in spite of the sameSSB #0, SSB #1, or SSB #2.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #0transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#0, index #4, index #0, and index #4, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #1transmitted in TU #0, TU #2, TU #4, and TU #6 may correspond to index#1, index #5, index #1, and index #5, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #2transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#2, index #6, index #2, and index #6, respectively.

In an exemplary embodiment, PBCH DM-RS sequences corresponding to SSB #3transmitted in TU #1, TU #3, TU #5, and TU #7 may correspond to index#3, index #7, index #3, and index #7, respectively.

In an exemplary embodiment, a DL signal corresponding to TU #0, TU #1,TU #2, and TU #3 may belong to sequence A.

In an exemplary embodiment, a DL signal corresponding to TU #4, TU #5,TU #6, and TU #7 may belong to sequence B.

According to various embodiments of the present disclosure, afterPSS/SSS detection, the UE may obtain slot boundary and/or indexinformation based on blind-detection of a DL signal and blind-detectionof a PBCH DM-RS sequence. However, SFN information may not be obtainedfrom a PBCH.

For example, it is assumed that L=4. In an exemplary embodiment, whenthe UE succeeds in detecting a sequence corresponding to PBCH DM-RSsequence index #0 and sequence B in the first L2 window and detecting asequence corresponding to PBCH DM-RS sequence index #4 and sequence A inthe L2 window after K [msec], the UE may identify that both SSBs are SSB#0.

Further, according to various embodiments of the present disclosure, theUE may obtain SFN information by combining PBCHs included in the twoSSBs. As described above, 3 LSBs of a PBCH DM-RS index may be used asthe second scrambling code of the PBCH in the NR system.

However, in various embodiments of the present disclosure describedabove, SFN information may be obtained through PBCH combining by usinglog 2(L) LSBs of a PBCH DM-RS index as the second scrambling code. Inthis example, since L=4, the UE should use only the log 2(L=4) LSBs ofthe PBCH DM-RS index, that is, 2 bits, as the second scrambling sequenceto obtain SFN information through PBCH combining.

3.3 From Perspective of RRM Measurement

According to various embodiments of the present disclosure, a UE mayperform RRM measurement for a serving cell and a neighboring cell tosupport mobility. According to various embodiments of the presentdisclosure, the UE may report RRM measurement information derived fromthe RRM measurement. In an exemplary embodiment, the RRM measurementinformation may be, but not limited to, RSRP or RSRQ.

Specifically, according to various embodiments of the presentdisclosure, the UE may perform RRM measurement based on an SSB (e.g., anSSS and a PBCH DM-RS) and/or a CSI-RS on a cell basis (or on a beambasis).

Particularly, various embodiments of the present disclosure descriedbelow relate to methods of performing RRM measurement based on an SSB bya UE. In an exemplary embodiment, an SSB may be transmitted to a UE inthe methods according to various embodiments of the present disclosure,described before in subclause 3.1.

In various embodiments of the present disclosure described below, it isassumed that the UE has acquired time and frequency synchronization forRRM measurement of the serving cell/neighboring cell. Variousembodiments of the present disclosure described below may also beapplied in the same manner in RLM and/or beam management, which couldeasily be understood by those skilled in the art.

3.3.1. [Method 1]

According to various embodiments of the present disclosure, afterblind-detecting an SSB index within an L2 window, the UE may measure SSBquality corresponding to the same SSB index.

That is, according to various embodiments of the present disclosure, theUE may blind-detect an SSB index within an L2 window. Then, the UE mayperform RRM measurement by measuring the quality of an SSB correspondingto the detected SSB index.

Referring to FIG. 21 , particularly when L1<{transmission duration of L(or L′) SSBs}, the UE may not identify an SSB to be transmitted afterthe first L1 time of the L2 window. Particularly in this case, a methodof measuring the quality of an SSB according to various embodiments ofthe present disclosure may be applied.

3.3.3. [Method 2]<Option 1. Shifted SSB Transmission>

Referring to FIG. 22 , for example, when L1>{transmission duration of LSSBs}, the index of an SSB to be transmitted at a specific time withinan L2 window may be fixed. Therefore, according to various embodimentsof the present disclosure, the UE may measure the quality of SSBscorresponding to the same SSB index without blind-detection of the SSBindex, compared to method 1 described in subclause 3.3.1.

According to various embodiments of the present disclosure in methods 3,4 and 5 described in subclause 3.2, even the same SSBs may havedifferent PBCH DM-RS sequences and/or SSS sequences and/or separate DLsignal sequences.

For example, it is assumed that L=4. In an exemplary embodiment, a PBCHDM-RS sequence corresponding to SSB index #0 may be transmitted in anSSB transmitted in the first TU of an L2 window. In an exemplaryembodiment, a PBCH DM-RS sequence corresponding to SSB index #4 may betransmitted in an SSB transmitted in the third TU of an L2 window afterK [msec].

In an exemplary embodiment, upon receipt of the two SSBs, the UE mayidentify that the two SSBs are the same because L=4. In an exemplaryembodiment, the UE may perform L1 and/or L3 filtering on a measurementresult corresponding to SSB index #0 in the first L2 window and ameasurement result corresponding to SSB index #4 in the next L2 window.

3.3.3. [Method 3]<Option 2. Cyclically Rotated SSB Transmission>

In an exemplary embodiment, even when the value of L1 is a function ofthe transmission duration L′ as illustrated in FIG. 23 and the value ofL1 is independent of the transmission duration L′ as illustrated in FIG.24 , the UE may perform measurement without blind-detection of an SSBindex (compared to the methods according to various embodiments of thepresent disclosure described in subclause 3.3.1.), only when the UE hasknowledge of L′ and/or L. According to various embodiments of thepresent disclosure, L′ may be replaced with L1.

-   -   Alt 1: According to various embodiments of the present        disclosure, the BS may signal L′ to the UE on a cell ID basis.        In an exemplary embodiment, the BS may signal L′ to the UE on a        cell ID basis by a cell-specific RRC signal and/or a UE-specific        RRC signal and/or SIB3 and/or SIB4. According to various        embodiments of the present disclosure, the UE may obtain cell ID        information based on PSS/SSS detection and perform measurement        based on the value of L′ corresponding to the obtained cell ID        without ambiguity about an SSB index at a specific time in the        L2 window.

According to various embodiments of the present disclosure, which one of(predefined) limited values is L′ may be configured for or indicated tothe UE. In other words, according to various embodiments of the presentdisclosure, values available as L′ may be predefined and a specific oneof the predefined values may be signaled to the UE.

In an exemplary embodiment, L′ may be limited to 4 or 8. In an exemplaryembodiment, the BS may signal to the UE whether L′ is 4 or 8 by one bitof a cell-specific RRC signal or a UE-specific RRC signal.

In an exemplary embodiment, L′ may be limited to an even number (2, 4,6, or 8). In an exemplary embodiment, the BS may signal to the UE whichone of 2, 4, 6, or 8 is L′ by two bits of a cell-specific RRC signal ora UE-specific RRC signal.

In an exemplary embodiment, L′ may be limited to a factor of 8, (1, 2, 4or 8). In an exemplary embodiment, the BS may signal to the UE which oneof 1, 2, 4, or 8 is L′ by two bits of a cell-specific RRC signal or aUE-specific RRC signal.

According to various embodiments of the present disclosure, it may begenerated that values available as L′ are predetermined, and apredetermined set including a plurality of candidate values isconfigured. The BS may indicate to the UE which one of the candidatevalues is L′ by a cell-specific RRC signal or a UE-specific RRC signal.

According to various embodiments of the present disclosure, thepredetermined value among the plurality of candidate values may beindicated by bits configured in the cell-specific RRC signal or theUE-specific RRC signal, and the number of the bits may be equal to thenumber of the plurality of candidate values in the predetermined set.

-   -   Alt 1a: According to various embodiments of the present        disclosure, the UE may have detected a cell ID for which an L′        value has not been received (e.g., although the UE has received        an L′ value corresponding to a certain cell ID as described in        Alt 1). That is, although the UE receives the cell ID, the UE        may not know the L′ value corresponding to the cell ID.

According to various embodiments of the present disclosure, in thiscase, a rule may be defined or configured so that the UE assumes aspecific value of L′. In an exemplary embodiment, the UE may assume thatL′=8 in this case. In an exemplary embodiment, in this case, the UE mayassume that L′ is the maximum one of available values. In an exemplaryembodiment, in this case, the UE may assume L′ as the value of L′ of theserving cell.

Even though the UE is configured to report quality for each beam index(i.e., beam-level quality), the UE may have difficulty in performingbeam-level RRM measurement for a cell ID in the above case because theUE has not been configured with an accurate value of L′ for the cell ID.According to various embodiments of the present disclosure, in thiscase, it may be regulated that the UE reports only a measured cell-levelquality during reporting of an RRM measurement corresponding to acorresponding cell ID and reports a specific value during reporting of abeam-level quality. In an exemplary embodiment, in this case, it may beregulated that the UE reports a value corresponding to the lowestquality (among measured cell-level qualities and/or values that the UEmay report regardless of the measured cell-level qualities) as thebeam-level quality.

-   -   Alt 2: According to various embodiments of the present        disclosure, the UE may perform measurement on the assumption        that L′ of a neighboring cell is equal to L′ of the serving        cell.    -   Alt 2a: According to various embodiments of the present        disclosure, the BS may signal an S value to the UE separately        from the L′ value of the serving cell. According to various        embodiments of the present disclosure, the UE may perform        measurement on the assumption that all (intra-frequency)        neighboring cells subject to (intra-frequency) measurement        transmit S SSBs.

Meanwhile, according to various embodiments of the present disclosure,it may be regulated that the UE assumes a specific S value, when an Svalue is not signaled separately. In an exemplary embodiment, the UE mayassume that S=8 in this case. In an exemplary embodiment, in this case,the UE may assume that S is the maximum of available values.

-   -   Alt 2b: According to various embodiments of the present        disclosure, the BS may signal to the UE whether it is possible        to assume that L′ of the serving cell is equal to L′ of the        neighboring cell. That is, according to various embodiments of        the present disclosure, the BS may signal to the UE whether it        is possible to assume that L′ of the serving cell is equal to L′        of the neighboring cell by cell-specific RRC signaling and/or        UE-specific RRC signaling. In an exemplary embodiment, the        cell-specific RRC signaling may be, but not limited to, a PBCH,        RMSI, OSI, or the like.

According to various embodiments of the present disclosure, when the UEis configured or indicated by the BS to assume that L′ of the servingcell and L′ of the neighboring cell are equal, the UE may performmeasurement in the method of Alt 2 according to various embodiments ofthe present disclosure described above.

According to various embodiments of the present disclosure, when the UEis configured or indicated by the BS not to assume that L′ of theserving cell and L′ of the neighboring cell are equal, the UE mayperform measurement in the method of Alt 1a according to variousembodiments of the present disclosure described above.

-   -   Alt 3: According to various embodiments of the present        disclosure, the UE may average the measurements of SSBs detected        at time points within an L2 window and report the average. That        is, according to various embodiments of the present disclosure,        the UE may measure only SSBs detected in each L2 window,        calculate the averages of the measurements of each of the SSBs        over L2 windows, and report the averages to the BS on an L2        window basis.

Referring to FIG. 23 , for example, there may be 16 SSB occasions in anL2 window. In an exemplary embodiment, the UE may calculate the averageof measurements of each occasion over L2 windows and report up to 16measurements. In an exemplary embodiment, the UE may report up to 16L1-filtered measurements to a higher layer and report beam-level and/orcell-level measurement results (after L3 filtering) to the BS.

-   -   Alt 4: According to various embodiments of the present        disclosure, the UE may directly obtain the value of L′ by        decoding system information multiplexed with an SSB, transmitted        from a neighboring cell. According to various embodiments of the        present disclosure, the UE may obtain information about a cell        ID by detecting a PSS/SSS and obtain the value of L′        corresponding to the obtained cell ID. According to various        embodiments of the present disclosure, the UE may perform        measurement based on the obtained value of L′ without ambiguity        about an SSB index at a specific time in the L2 window.    -   Alt 5: According to various embodiments of the present        disclosure, the serving cell may signal to the UE information        about the number of beam indexes and/or the number of SSB        indexes and/or the number of PBCH DM-RS sequence indexes, which        the UE may assume when measuring (the neighboring cell).

In an exemplary embodiment, when the number of SSB indexes is indicatedas K to the UE, the UE may measure SSBs corresponding to indexes {0, 1,. . . , K−1} derived from a combination of an SSB index and/or a PBCHDM-RS sequence index and/or a PBCH DM-RS sequence and PBCH payload in ameasurement window.

According to various embodiments of the present disclosure, when adownlink burst at least including an SSB burst set is defined as adiscovery signal or discovery reference signal (DRS), a DRS measurementtiming configuration (DMTC) may be defined. According to variousembodiments of the present disclosure, a DMTC for RRM or RLM measurementmay be configured (individually), and this DMTC may be an example of theafore-mentioned measurement window.

-   -   Alt 6: According to various embodiments of the present        disclosure, the serving cell may signal to the UE information        about a beam index and/or an SSB index and/or a PBCH DM-RS        sequence index and/or an index derived from a combination of        PBCH DM-RS sequence and PBCH payload, which the UE may assume        when measuring (the neighboring cell).

In an exemplary embodiment, the information may be L-bit bitmapinformation. Assuming L=4, for example, the UE receiving bitmapinformation of [1 0 1 0] may perform measurement on SSB indexes #0 and#2 (and/or beam indexes #0 and #2 and/or PBCH DM-RS sequence index #0and #2 and/or indexes #0 and #2 derived from a combination of a PBCHDM-RS sequence and PBCH payload) in the L2 window.

According to various embodiments of the present disclosure, it may begeneralized that the corresponding information may be L-bit bitmapinformation [b 0, b 1, . . . , b L−1]. Each bit of the L-bit bitmap maycorrespond to a beam index and/or an SSB index and/or a PBCH DM-RSsequence index and/or an index derived from a combination of a PBCHDM-RS sequence and PBCH payload, subject to measurement during the L2window.

In an exemplary embodiment, when b₀=1, it may mean that the UE shouldperform measurement at SSB index #0. When b₀=0, it may mean that the UEshould not perform measurement at SSB index #0.

-   -   Alt 7: According to various embodiments of the present        disclosure, the serving cell or the BS may signal to the UE        information about a timing at which the UE should (a neighboring        cell) measurement within a measurement window (e.g., the        afore-mentioned DMTC).

In an exemplary embodiment, the information may be L-bit bitmapinformation. Assuming that L=4, for example, the UE receiving bitmapinformation of [1 1 0 0] may interpret the bitmap information as itsrepetition during the L2 window, [1 1 0 0 1 1 0 0 1 1 0 0 . . . ] andperform measurement only at positions corresponding to a value of 1′.According to various embodiments of the present disclosure, the numberof SSB candidate positions in the L2 window may be equal to the numberof elements of the repeated bitmap information array.

-   -   Opt 1: According to various embodiments of the present        disclosure, the UE may perform measurement at positions        corresponding to ‘1’, assuming all beam indexes and/or SSB        indexes and/or PBCH DM-RS sequence indexes and/or indexes        derived from combinations of PBCH DM-RS sequences and PBCH        payload.    -   Opt 2: According to various embodiments of the present        disclosure, the UE may perform measurement for beam index #0        and/or SSB index #0 and/or PBCH DM-RS sequence index #0 and/or        index #0 derived from a combination of a PBCH DM-RS sequence and        PBCH payload at a position in which the first bit is repeated        among 4-bit bitmap repetitions. According to various embodiments        of the present disclosure, the UE may perform measurement for        beam index #1 and/or SSB index #1 and/or PBCH DM-RS sequence        index #1 and/or index #1 derived from a combination of a PBCH        DM-RS sequence and PBCH payload at a position in which the        second bit is repeated among 4-bit bitmap repetitions.    -   Opt 3: According to various embodiments of the present        disclosure, the UE may perform measurement for beam indexes #0/1        and/or SSB index #0/1 and/or PBCH DM-RS sequence #0/1 and/or        index #0/1 derived from a combination of a PBCH DM-RS sequence        and PBCH payload by mapping each bit of the 4-bit bitmap        information to a beam index and/or an SSB index and/or a PBCH        DM-RS sequence index and/or an index derived from a combination        of a PBCH DM-RS sequence and PBCH payload. The UE may perform        measurement only at positions corresponding to ‘1’, interpreting        time resources to be measured as repeated bitmap information.    -   Alt 8: According to various embodiments of the present        disclosure, the serving cell or the BS may signal to the UE        information about timings and beam indexes (and/or SSB indexes        and/or PBCH DM-RS sequence indexes and/or indexes derived from        combinations of PBCH DM-RS sequences and PBCH payload) at which        the UE should perform (neighboring cell) measurement in a        measurement window (e.g., the afore-mentioned DMTC).

In an exemplary embodiment, the information may be L-bit bitmapinformation and information about the number M. Assuming that L=4, forexample, the UE receiving bitmap information of [1 1 0 0] and 3 (M=3) asthe number information may interpret the bitmap information as bitmapinformation obtained by the first three bits of the received bitmapinformation during the L2 window, [1 1 0 1 1 0 1 1 0 . . . ], andperform measurement only at positions corresponding to a value of ‘1’.According to various embodiments of the present disclosure, the numberof SSB candidate positions in the L2 window may be equal to the numberof elements of the repeated bitmap information array.

-   -   Opt A: According to various embodiments of the present        disclosure, the UE may perform measurement at positions        corresponding to ‘1’, assuming all beam indexes and/or SSB        indexes and/or PBCH DM-RS sequence indexes and/or all indexes        derived from combinations of PBCH DM-RS sequences and PBCH        payload.    -   Opt 2: According to various embodiments of the present        disclosure, the UE may perform measurement for beam index #0        and/or SSB index #0 and/or PBCH DM-RS sequence #0 and/or index        #0 derived from a combination of a PBCH DM-RS sequence and PBCH        payload at a position in which the first bit is repeated among        4-bit bitmap repetitions. According to various embodiments of        the present disclosure, the UE may perform measurement for beam        index #1 and/or SSB index #1 and/or PBCH DM-RS sequence #1        and/or index #1 derived from a combination of a PBCH DM-RS        sequence and PBCH payload at a position in which the second bit        is repeated among 4-bit bitmap repetitions.    -   Opt C: According to various embodiments of the present        disclosure, the UE may perform measurement for beam index #0/1        and/or SSB index #0/1 and/or PBCH DM-RS sequence #0/1 and/or        index #0/1 derived from a combination of a PBCH DM-RS sequence        and PBCH payload by mapping each bit of the 4-bit bitmap        information to a beam index and/or an SSB index and/or a PBCH        DM-RS sequence index and/or an index derived from a combination        of a PBCH DM-RS sequence and PBCH payload. The UE may perform        measurement only at positions corresponding to ‘1’, interpreting        time resources to be measured as repeated bitmap information.

3.3.4 [Method 4]

Referring to FIG. 24 , for example, when the value of L1 is independentof the transmission duration L′, the index of an SSB to be transmittedat a specific time within an L2 window may be fixed. Therefore,according to various embodiments of the present disclosure, the UE maymeasure the quality of SSBs corresponding to the same SSB index withoutblind-detection of the SSB index, compared to the methods described insubclause 3.3.1.

According to various embodiments of the present disclosure in methods 3,4 and 5 described in subclause 3.2, even the same SSBs may havedifferent PBCH DM-RS sequences and/or SSS sequences and/or separate DLsignal sequences.

Referring to FIG. 24 , for example, it is assumed that L=4. In anexemplary embodiment, a PBCH DM-RS sequence corresponding to SSB index#0 may be transmitted in an SSB transmitted in the first TU of an L2window. In an exemplary embodiment, a PBCH DM-RS sequence correspondingto SSB index #4 may be transmitted in an SSB transmitted in the third TUof an L2 window after K [msec]. In an exemplary embodiment, upon receiptof the two SSBs, the UE may identify that the two SSBs are the samebecause L=4. In an exemplary embodiment, the UE may perform L1 and/or L3filtering on a measurement result corresponding to SSB index #0 in thefirst L2 window and a measurement result corresponding to SSB index #4in the next L2 window.

3.3.3. [Method 5]

Referring to FIG. 23 , when the value of L1 is a function of thetransmission duration L′, and when the neighboring cell and the servingcell are not accurately synchronized with each other, the UE may faceambiguity about the position of the next SSB even though the UE detectsan SSB from the neighboring cell within an L2 window.

For example, (on the assumption of Case A/C among SSB transmissionschemes of the NR system,) when the UE detects SSB #2 in the firsthalf-slot of TU #1 from the neighboring cell, the next SSB candidateposition of the neighboring cell may be 2 symbols after the endingsymbol of SSB #2. For example, when the UE detects SSB #2 in the secondhalf-slot of TU #5 from the neighboring cell, the next SSB candidateposition of the neighboring cell may be 4 symbols after the endingsymbol of SSB #2. However, the UE may have difficulty in obtaininginformation about the transmission duration L′ of the neighboring cell.In this case, even though the UE detects SSB #2, the UE may suffer fromambiguity about the position of the next SSB.

To solve this problem, according to various embodiments of the presentdisclosure, limitations may be imposed on the index of an SSBtransmitted in the first half-slot and the index of an SSB transmittedin the second half-slot.

In an exemplary embodiment, the index of an SSB transmitted in the firsthalf-slot may be an even value.

In an exemplary embodiment, the index of an SSB transmitted in thesecond half-slot may be an odd value.

In an exemplary embodiment, the index of a PBCH DM-RS sequencetransmitted in the first half-slot may be an even value.

In an exemplary embodiment, the index of a PBCH DM-RS sequencetransmitted in the second half-slot may be an odd value.

In an exemplary embodiment, when the index of an SSB and/or the index ofa PBCH DM-RS sequence that the UE has detected from a specificneighboring cell is an even value, the UE may identify that the SSB hasbeen transmitted in the first half-slot. In an exemplary embodiment, theUE may identify that the next SSB candidate position of the neighboringcell is 2 symbols after the SSB.

The various embodiments of the present disclosure described above aresome of various implementation schemes of the present disclosure, and itis clearly understood by those skilled in the art that variousembodiments of the present disclosure are not limited to theabove-described embodiments. While the various embodiments of thepresent disclosure described above may be independently implemented,other various embodiments of the present disclosure may be configured bycombining (or merging) some embodiments. It may be regulated thatinformation indicating whether to apply the various embodiments of thepresent disclosure described above (or information about the rules ofthe various embodiments of the present disclosure described above) isindicated by a signal (e.g., a physical-layer signal or a higher-layersignal) predefined for the UE by the BS.

3.4. Initial Network Access and Communication Process

The UE may perform a network access process to perform theabove-described/proposed procedures and/or methods. For example, the UEmay receive and store system information and configuration informationrequired to perform the above-described/proposed procedures and/ormethods during network access (e.g., BS access). The configurationinformation required for the present disclosure may be received byhigher-layer signaling (e.g., RRC signaling or MAC-layer signaling).

FIG. 27 is a diagram illustrating an initial network access andsubsequent communication process. In the NR system to which variousembodiments of the present disclosure, a physical channel and an RS maybe transmitted by beamforming. When beamforming-based signaltransmission is supported, beam management may follow for beam alignmentbetween a BS and a UE. Further, a signal proposed in various embodimentsof the present disclosure may be transmitted/received by beamforming. InRRC_IDLE mode, beam alignment may be performed based on an SSB (orSS/PBCH block), whereas in RRC_CONNECTED mode, beam alignment may beperformed based on a CSI-RS (in DL) and an SRS (in UL). On the contrary,when beamforming-based signal transmission is not supported,beam-related operations in the following description may be skipped.

Referring to FIG. 27 , a BS (e.g., eNB) may periodically transmit an SSB(S2702). The SSB includes a PSS/SSS/PBCH. The SSB may be transmitted bybeam sweeping. The BS may then transmit RMSI and other systeminformation (OSI) (S2704). The RMSI may include information required forthe UE to perform initial access to the BS (e.g., PRACH configurationinformation). After detecting SSBs, the UE identifies the best SSB. TheUE may then transmit an RACH preamble (Message 1; Msg1) in PRACHresources linked/corresponding to the index (i.e., beam) of the best SSB(S2706). The beam direction of the RACH preamble is associated with thePRACH resources. Association between PRACH resources (and/or RACHpreambles) and SSBs (SSB indexes) may be configured by systeminformation (e.g., RMSI). Subsequently, in an RACH procedure, the BS maytransmit a random access response (RAR) (Msg2) in response to the RACHpreamble (S2708), the UE may transmit Msg3 (e.g., RRC ConnectionRequest) based on a UL grant included in the RAR (S2710), and the BS maytransmit a contention resolution message (Msg4) (S2720). Msg4 mayinclude RRC Connection Setup.

When an RRC connection is established between the BS and the UE in theRACH procedure, beam alignment may subsequently be performed based on anSSB/CSI-RS (in DL) and an SRS (in UL). For example, the UE may receivean SSB/CSI-RS (S2714). The SSB/CSI-RS may be used for the UE to generatea beam/CSI report. The BS may request the UE to transmit a beam/CSIreport, by DCI (S2716). In this case, the UE may generate a beam/CSIreport based on the SSB/CSI-RS and transmit the generated beam/CSIreport to the BS on a PUSCH/PUCCH (S2718). The beam/CSI report mayinclude a beam measurement result, information about a preferred beam,and so on. The BS and the UE may switch beams based on the beam/CSIreport (S2720 a and S2720 b).

Subsequently, the UE and the BS may perform the above-described/proposedprocedures and/or methods. For example, the UE and the BS may transmit awireless signal by processing information stored in a memory or mayprocess a received wireless signal and store the processed signal in amemory according to the proposal of the present disclosure, based onconfiguration information obtained in a network access process (e.g., asystem information acquisition process, an RRC connection process on anRACH, and so on). The wireless signal may include at least one of aPDCCH, a PDSCH, or an RS on DL and at least one of a PUCCH, a PUSCH, oran SRS on UL.

FIG. 28 is a simplified diagram illustrating a signal flow for a methodof operating a UE and a BS according to various embodiments of thepresent disclosure.

FIG. 29 is a flowchart illustrating a method of operating a UE accordingto various embodiments of the present disclosure.

FIG. 30 is a flowchart illustrating a method of operating a BS accordingto various embodiments of the present disclosure.

Referring to FIGS. 28 to 30 , according to various embodiments of thepresent disclosure, the BS may perform a CAP for an unlicensed band(52801 and S2901).

According to various embodiments of the present disclosure, the BS maytransmit one or more SSBs in the unlicensed band based on the CAP, andthe UE may receive the SSBs (52803, 52903, and S3001).

In an exemplary embodiment, the one or more SSBs may be transmitted atone or more second consecutive candidate positions including a startingcandidate position determined based on the CAP among first candidatepositions configured within a time window.

In an exemplary embodiment, (optionally,) the UE may perform RRMmeasurement in response to the one or more SSBs (52805 and S3003). TheUE may report the RRM measurements, and the BS may receive the RRMmeasurements (52807, 52905, and S3005).

More detailed operations of the BS and/or the UE according to theabove-described various embodiments of the present disclosure may bedescribed and performed based on the contents of clause 1 to clause 3.

Because examples of the above-described proposed methods may also beincluded as one of the implementation methods of the present disclosure,it is obvious that they may be considered as a kind of proposed method.Further, while the above-described proposed methods may be implementedindependently, some of the proposed methods may be combined (or merged).It may be regulated that information indicating whether to apply thevarious embodiments of the present disclosure described above (orinformation about the rules of the various embodiments of the presentdisclosure described above) is indicated by a signal (e.g., aphysical-layer signal or a higher-layer signal) predefined for the UE bythe BS.

4. Apparatus Configuration

FIG. 31 is a diagram illustrating devices that implement variousembodiments of the present disclosure.

The devices illustrated in FIG. 31 may be a UE and/or a BS (e.g., eNB orgNB) adapted to perform the afore-described mechanisms, or any devicesperforming the same operation.

Referring to FIG. 31 , the device may include a digital signal processor(DSP)/microprocessor 210 and a radio frequency (RF) module (transceiver)235. The DSP/microprocessor 210 is electrically coupled to thetransceiver 235 and controls the transceiver 235. The device may furtherinclude a power management module 205, a battery 255, a display 215, akeypad 220, a SIM card 225, a memory device 230, an antenna 240, aspeaker 245, and an input device 250, depending on a designer'sselection.

Particularly, FIG. 31 may illustrate a UE including a receiver 235configured to receive a request message from a network and a transmitter235 configured to transmit timing transmission/reception timinginformation to the network. These receiver and transmitter may form thetransceiver 235. The UE may further include a processor 210 coupled tothe transceiver 235.

Further, FIG. 31 may illustrate a network device including a transmitter235 configured to transmit a request message to a UE and a receiver 235configured to receive timing transmission/reception timing informationfrom the UE. These transmitter and receiver may form the transceiver235. The network may further include the processor 210 coupled to thetransceiver 235. The processor 210 may calculate latency based on thetransmission/reception timing information.

A processor included in a UE (or a communication device included in theUE) and a BE (or a communication device included in the BS) according tovarious embodiments of the present disclosure may operate as follows,while controlling a memory.

According to various embodiments of the present disclosure, a UE or a BSmay include at least one transceiver, at least one memory, and at leastone processor coupled to the at least one transceiver and the at leastone memory. The at least one memory may store instructions causing theat least one processor to perform the following operations.

A communication device included in the UE or the BS may be configured toinclude the at least one processor and the at least one memory. Thecommunication device may be configured to include the at least onetransceiver, or may be configured not to include the at least onetransceiver but to be connected to the at least one transceiver.

According to various embodiments of the present disclosure, at least oneprocessor included in a BS (or at least one processor of a communicationdevice included in the BS) may perform a CAP for an unlicensed band.

According to various embodiments of the present disclosure, the at leastone processor included in the BS may transmit one or more SSBs in theunlicensed band based on the CAP.

In an exemplary embodiment, the one or more SSBs may be transmitted atone or more second consecutive candidate positions including a startingcandidate position determined based on the CAP among first candidatepositions configured within a time window.

According to various embodiments of the present disclosure, at least oneprocessor included in a UE (or at least one processor of a communicationdevice included in the UE) may receive one or more SSBs in an unlicensedband.

In an exemplary embodiment, the at least one processor included in theUE may (optionally) perform RRM measurement in response to the one ormore SSBs and report the RRM measurements.

More detailed operations of the BS and/or the UE according to theabove-described various embodiments of the present disclosure may bedescribed and performed based on the contents of clause 1 to clause 3.

Various embodiments of the present disclosure may be implemented incombination with each other, unless contradicting each other. Forexample, (a processor included in) a BS and/or a UE according to variousembodiments of the present disclosure may perform a combination/combinedoperation of the embodiments of clause 1 to clause 3 described above,unless contradicting each other.

In the present specification, various embodiments of the presentdisclosure have been described, focusing on a datatransmission/reception relationship between a BS and a UE in a wirelesscommunication system. However, various embodiments of the presentdisclosure are not limited thereto. For example, various embodiments ofthe present disclosure may also relate to the following technicalconfigurations.

Example of Communication System to which Various Embodiments of thePresent Disclosure are Applied

The various descriptions, functions, procedures, proposals, methods,and/or operational flowcharts of the various embodiments of the presentdisclosure described in this document may be applied to, without beinglimited to, a variety of fields requiring wirelesscommunication/connection (e.g., 5G) between devices.

Hereinafter, a description will be given in more detail with referenceto the drawings. In the following drawings/description, the samereference symbols may denote the same or corresponding hardware blocks,software blocks, or functional blocks unless described otherwise.

FIG. 32 illustrates an exemplary communication system to which variousembodiments of the present disclosure are applied.

Referring to FIG. 32 , a communication system 1 applied to the variousembodiments of the present disclosure includes wireless devices, BaseStations (BSs), and a network. Herein, the wireless devices representdevices performing communication using Radio Access Technology (RAT)(e.g., 5G New RAT (NR)) or Long-Term Evolution (LTE)) and may bereferred to as communication/radio/5G devices. The wireless devices mayinclude, without being limited to, a robot 100 a, vehicles 100 b-1 and100 b-2, an eXtended Reality (XR) device 100 c, a hand-held device 100d, a home appliance 100 e, an Internet of Things (IoT) device 100 f, andan Artificial Intelligence (AI) device/server 400. For example, thevehicles may include a vehicle having a wireless communication function,an autonomous driving vehicle, and a vehicle capable of performingcommunication between vehicles. Herein, the vehicles may include anUnmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may includean Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) deviceand may be implemented in the form of a Head-Mounted Device (HMD), aHead-Up Display (HUD) mounted in a vehicle, a television, a smartphone,a computer, a wearable device, a home appliance device, a digitalsignage, a vehicle, a robot, etc. The hand-held device may include asmartphone, a smartpad, a wearable device (e.g., a smartwatch or asmartglasses), and a computer (e.g., a notebook). The home appliance mayinclude a TV, a refrigerator, and a washing machine. The IoT device mayinclude a sensor and a smartmeter. For example, the BSs and the networkmay be implemented as wireless devices and a specific wireless device200 a may operate as a B S/network node with respect to other wirelessdevices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g.,NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,sidelink communication) with each other without passing through theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. Vehicle-to-Vehicle(V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may beestablished between the wireless devices 100 a to 100 f/BS 200, or BS200/BS 200. Herein, the wireless communication/connections may beestablished through various RATs (e.g., 5G NR) such as uplink/downlinkcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter BS communication (e.g. relay, Integrated AccessBackhaul (IAB)). The wireless devices and the BSs/the wireless devicesmay transmit/receive radio signals to/from each other through thewireless communication/connections 150 a and 150 b. For example, thewireless communication/connections 150 a and 150 b may transmit/receivesignals through various physical channels. To this end, at least a partof various configuration information configuring processes, varioussignal processing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocating processes, for transmitting/receiving radio signals, may beperformed based on the various proposals of the various embodiments ofthe present disclosure.

Example of Wireless Devices to which Various Embodiments of the PresentDisclosure are Applied

FIG. 33 illustrates exemplary wireless devices to which variousembodiments of the present disclosure are applicable.

Referring to FIG. 33 , a first wireless device 100 and a second wirelessdevice 200 may transmit radio signals through a variety of RATs (e.g.,LTE and NR). Herein, {the first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 100 x andthe BS 200} and/or {the wireless device 100 x and the wireless device100 x} of FIG. 32 .

The first wireless device 100 may include one or more processors 102 andone or more memories 104 and additionally further include one or moretransceivers 106 and/or one or more antennas 108. The processor(s) 102may control the memory(s) 104 and/or the transceiver(s) 106 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 102 may process informationwithin the memory(s) 104 to generate first information/signals and thentransmit radio signals including the first information/signals throughthe transceiver(s) 106. The processor(s) 102 may receive radio signalsincluding second information/signals through the transceiver 106 andthen store information obtained by processing the secondinformation/signals in the memory(s) 104. The memory(s) 104 may beconnected to the processor(s) 102 and may store a variety of informationrelated to operations of the processor(s) 102. For example, thememory(s) 104 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 102or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 102 and the memory(s) 104 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 106 may be connected to the processor(s) 102 andtransmit and/or receive radio signals through one or more antennas 108.Each of the transceiver(s) 106 may include a transmitter and/or areceiver. The transceiver(s) 106 may be interchangeably used with RadioFrequency (RF) unit(s). In the various embodiments of the presentdisclosure, the wireless device may represent a communicationmodem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204 and additionally further include one ormore transceivers 206 and/or one or more antennas 208. The processor(s)202 may control the memory(s) 204 and/or the transceiver(s) 206 and maybe configured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process informationwithin the memory(s) 204 to generate third information/signals and thentransmit radio signals including the third information/signals throughthe transceiver(s) 206. The processor(s) 202 may receive radio signalsincluding fourth information/signals through the transceiver(s) 106 andthen store information obtained by processing the fourthinformation/signals in the memory(s) 204. The memory(s) 204 may beconnected to the processor(s) 202 and may store a variety of informationrelated to operations of the processor(s) 202. For example, thememory(s) 204 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 202 and the memory(s) 204 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 206 may be connected to the processor(s) 202 andtransmit and/or receive radio signals through one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the various embodiments of the present disclosure, thewireless device may represent a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors 102 and202. For example, the one or more processors 102 and 202 may implementone or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP,RRC, and SDAP). The one or more processors 102 and 202 may generate oneor more Protocol Data Units (PDUs) and/or one or more Service Data Unit(SDUs) according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Theone or more processors 102 and 202 may generate messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document and provide thegenerated signals to the one or more transceivers 106 and 206. The oneor more processors 102 and 202 may receive the signals (e.g., basebandsignals) from the one or more transceivers 106 and 206 and acquire thePDUs, SDUs, messages, control information, data, or informationaccording to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. As an example, one or moreApplication Specific Integrated Circuits (ASICs), one or more DigitalSignal Processors (DSPs), one or more Digital Signal Processing Devices(DSPDs), one or more Programmable Logic Devices (PLDs), or one or moreField Programmable Gate Arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be implemented using firmware or software and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or stored in the one or more memories 104 and 204 so as tobe driven by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured by Read-OnlyMemories (ROMs), Random Access Memories (RAMs), Electrically ErasableProgrammable Read-Only Memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in the methodsand/or operational flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, from one or moreother devices. For example, the one or more transceivers 106 and 206 maybe connected to the one or more processors 102 and 202 and transmit andreceive radio signals. For example, the one or more processors 102 and202 may perform control so that the one or more transceivers 106 and 206may transmit user data, control information, or radio signals to one ormore other devices. The one or more processors 102 and 202 may performcontrol so that the one or more transceivers 106 and 206 may receiveuser data, control information, or radio signals from one or more otherdevices. The one or more transceivers 106 and 206 may be connected tothe one or more antennas 108 and 208 and the one or more transceivers106 and 206 may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, through the one ormore antennas 108 and 208. In this document, the one or more antennasmay be a plurality of physical antennas or a plurality of logicalantennas (e.g., antenna ports). The one or more transceivers 106 and 206may convert received radio signals/channels etc. from RF band signalsinto baseband signals in order to process received user data, controlinformation, radio signals/channels, etc. using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, radio signals/channels, etc.processed using the one or more processors 102 and 202 from the baseband signals into the RF band signals. To this end, the one or moretransceivers 106 and 206 may include (analog) oscillators and/orfilters.

Example of Using Wireless Devices to which Various Embodiments of thePresent Disclosure are Applied

FIG. 34 illustrates other exemplary wireless devices to which variousembodiments of the present disclosure are applied. The wireless devicesmay be implemented in various forms according to a use case/service (seeFIG. 32 ).

Referring to FIG. 34 , wireless devices 100 and 200 may correspond tothe wireless devices 100 and 200 of FIG. 33 and may be configured byvarious elements, components, units/portions, and/or modules. Forexample, each of the wireless devices 100 and 200 may include acommunication unit 110, a control unit 120, a memory unit 130, andadditional components 140. The communication unit may include acommunication circuit 112 and transceiver(s) 114. For example, thecommunication circuit 112 may include the one or more processors 102 and202 and/or the one or more memories 104 and 204 of FIG. 33 . Forexample, the transceiver(s) 114 may include the one or more transceivers106 and 206 and/or the one or more antennas 108 and 208 of FIG. 33 . Thecontrol unit 120 is electrically connected to the communication unit110, the memory 130, and the additional components 140 and controlsoverall operation of the wireless devices. For example, the control unit120 may control an electric/mechanical operation of the wireless devicebased on programs/code/commands/information stored in the memory unit130. The control unit 120 may transmit the information stored in thememory unit 130 to the exterior (e.g., other communication devices) viathe communication unit 110 through a wireless/wired interface or store,in the memory unit 130, information received through the wireless/wiredinterface from the exterior (e.g., other communication devices) via thecommunication unit 110.

The additional components 140 may be variously configured according totypes of wireless devices. For example, the additional components 140may include at least one of a power unit/battery, input/output (I/O)unit, a driving unit, and a computing unit. The wireless device may beimplemented in the form of, without being limited to, the robot (100 aof FIG. 32 ), the vehicles (100 b-1 and 100 b-2 of FIG. 32 ), the XRdevice (100 c of FIG. 32 ), the hand-held device (100 d of FIG. 32 ),the home appliance (100 e of FIG. 32 ), the IoT device (100 f of FIG. 32), a digital broadcast terminal, a hologram device, a public safetydevice, an MTC device, a medicine device, a fintech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 32 ), the BSs (200 of FIG. 32 ), a networknode, etc. The wireless device may be used in a mobile or fixed placeaccording to a use-example/service.

In FIG. 34 , the entirety of the various elements, components,units/portions, and/or modules in the wireless devices 100 and 200 maybe connected to each other through a wired interface or at least a partthereof may be wirelessly connected through the communication unit 110.For example, in each of the wireless devices 100 and 200, the controlunit 120 and the communication unit 110 may be connected by wire and thecontrol unit 120 and first units (e.g., 130 and 140) may be wirelesslyconnected through the communication unit 110. Each element, component,unit/portion, and/or module within the wireless devices 100 and 200 mayfurther include one or more elements. For example, the control unit 120may be configured by a set of one or more processors. As an example, thecontrol unit 120 may be configured by a set of a communication controlprocessor, an application processor, an Electronic Control Unit (ECU), agraphical processing unit, and a memory control processor. As anotherexample, the memory 130 may be configured by a Random Access Memory(RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory,a volatile memory, a non-volatile memory, and/or a combination thereof.

Hereinafter, an example of implementing FIG. 34 will be described indetail with reference to the drawings.

Example of Portable Device to which Various Embodiments of the PresentDisclosure are Applied

FIG. 35 illustrates an exemplary portable device to which variousembodiments of the present disclosure are applied. The portable devicemay be any of a smartphone, a smartpad, a wearable device (e.g., asmartwatch or smart glasses), and a portable computer (e.g., a laptop).A portable device may also be referred to as mobile station (MS), userterminal (UT), mobile subscriber station (MSS), subscriber station (SS),advanced mobile station (AMS), or wireless terminal (WT).

Referring to FIG. 35 , a hand-held device 100 may include an antennaunit 108, a communication unit 110, a control unit 120, a memory unit130, a power supply unit 140 a, an interface unit 140 b, and an I/O unit140 c. The antenna unit 108 may be configured as a part of thecommunication unit 110. Blocks 110 to 130/140 a to 140 c correspond tothe blocks 110 to 130/140 of FIG. 34 , respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from other wireless devices or BSs. Thecontrol unit 120 may perform various operations by controllingconstituent elements of the hand-held device 100. The control unit 120may include an Application Processor (AP). The memory unit 130 may storedata/parameters/programs/code/commands needed to drive the hand-helddevice 100. The memory unit 130 may store input/output data/information.The power supply unit 140 a may supply power to the hand-held device 100and include a wired/wireless charging circuit, a battery, etc. Theinterface unit 140 b may support connection of the hand-held device 100to other external devices. The interface unit 140 b may include variousports (e.g., an audio I/O port and a video I/O port) for connection withexternal devices. The I/O unit 140 c may input or output videoinformation/signals, audio information/signals, data, and/or informationinput by a user. The I/O unit 140 c may include a camera, a microphone,a user input unit, a display unit 140 d, a speaker, and/or a hapticmodule.

As an example, in the case of data communication, the I/O unit 140 c mayacquire information/signals (e.g., touch, text, voice, images, or video)input by a user and the acquired information/signals may be stored inthe memory unit 130. The communication unit 110 may convert theinformation/signals stored in the memory into radio signals and transmitthe converted radio signals to other wireless devices directly or to aBS. The communication unit 110 may receive radio signals from otherwireless devices or the BS and then restore the received radio signalsinto original information/signals. The restored information/signals maybe stored in the memory unit 130 and may be output as various types(e.g., text, voice, images, video, or haptic) through the I/O unit 140c.

Example of Vehicle or Autonomous Driving Vehicle to which VariousEmbodiments of the Present Disclosure.

FIG. 36 illustrates an exemplary vehicle or autonomous driving vehicleto which various embodiments of the present disclosure. The vehicle orautonomous driving vehicle may be implemented as a mobile robot, a car,a train, a manned/unmanned aerial vehicle (AV), a ship, or the like.

Referring to FIG. 36 , a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. The blocks110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 34 ,respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an Electronic Control Unit (ECU). The driving unit 140 a maycause the vehicle or the autonomous driving vehicle 100 to drive on aroad. The driving unit 140 a may include an engine, a motor, apowertrain, a wheel, a brake, a steering device, etc. The power supplyunit 140 b may supply power to the vehicle or the autonomous drivingvehicle 100 and include a wired/wireless charging circuit, a battery,etc. The sensor unit 140 c may acquire a vehicle state, ambientenvironment information, user information, etc. The sensor unit 140 cmay include an Inertial Measurement Unit (IMU) sensor, a collisionsensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor,a heading sensor, a position module, a vehicle forward/backward sensor,a battery sensor, a fuel sensor, a tire sensor, a steering sensor, atemperature sensor, a humidity sensor, an ultrasonic sensor, anillumination sensor, a pedal position sensor, etc. The autonomousdriving unit 140 d may implement technology for maintaining a lane onwhich a vehicle is driving, technology for automatically adjustingspeed, such as adaptive cruise control, technology for autonomouslydriving along a determined path, technology for driving by automaticallysetting a path if a destination is set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, etc. from an external server. The autonomous drivingunit 140 d may generate an autonomous driving path and a driving planfrom the obtained data. The control unit 120 may control the drivingunit 140 a such that the vehicle or the autonomous driving vehicle 100may move along the autonomous driving path according to the driving plan(e.g., speed/direction control). In the middle of autonomous driving,the communication unit 110 may aperiodically/periodically acquire recenttraffic information data from the external server and acquiresurrounding traffic information data from neighboring vehicles. In themiddle of autonomous driving, the sensor unit 140 c may obtain a vehiclestate and/or surrounding environment information. The autonomous drivingunit 140 d may update the autonomous driving path and the driving planbased on the newly obtained data/information. The communication unit 110may transfer information about a vehicle position, the autonomousdriving path, and/or the driving plan to the external server. Theexternal server may predict traffic information data using AItechnology, etc., based on the information collected from vehicles orautonomous driving vehicles and provide the predicted trafficinformation data to the vehicles or the autonomous driving vehicles.

In summary, various embodiments of the present disclosure may beimplemented through a certain device and/or UE.

For example, the certain device may be any of a BS, a network node, atransmitting UE, a receiving UE, a wireless device, a wirelesscommunication device, a vehicle, a vehicle equipped with an autonomousdriving function, an unmanned aerial vehicle (UAV), an artificialintelligence (AI) module, a robot, an augmented reality (AR) device, avirtual reality (VR) device, and other devices.

For example, a UE may be any of a personal digital assistant (PDA), acellular phone, a personal communication service (PCS) phone, a globalsystem for mobile (GSM) phone, a wideband CDMA (WCDMA) phone, a mobilebroadband system (MB S) phone, a smartphone, and a multi mode-multi band(MM-MB) terminal.

A smartphone refers to a terminal taking the advantages of both a mobilecommunication terminal and a PDA, which is achieved by integrating adata communication function being the function of a PDA, such asscheduling, fax transmission and reception, and Internet connection in amobile communication terminal. Further, an MM-MB terminal refers to aterminal which has a built-in multi-modem chip and thus is operable inall of a portable Internet system and other mobile communication system(e.g., CDMA 2000, WCDMA, and so on).

Alternatively, the UE may be any of a laptop PC, a hand-held PC, atablet PC, an ultrabook, a slate PC, a digital broadcasting terminal, aportable multimedia player (PMP), a navigator, and a wearable devicesuch as a smart watch, smart glasses, and a head mounted display (HMD).For example, a UAV may be an unmanned aerial vehicle that flies underthe control of a wireless control signal. For example, an HMD may be adisplay device worn around the head. For example, the HMD may be used toimplement AR or VR.

Various embodiments of the present disclosure may be implemented invarious means. For example, various embodiments of the presentdisclosure may be implemented in hardware, firmware, software, or acombination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present disclosure may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to thevarious embodiments of the present disclosure may be implemented in theform of a module, a procedure, a function, etc. performing theabove-described functions or operations. A software code may be storedin the memory 50 or 150 and executed by the processor 40 or 140. Thememory is located at the interior or exterior of the processor and maytransmit and receive data to and from the processor via various knownmeans.

Those skilled in the art will appreciate that the various embodiments ofthe present disclosure may be carried out in other specific ways thanthose set forth herein without departing from the spirit and essentialcharacteristics of the various embodiments of the present disclosure.The above embodiments are therefore to be construed in all aspects asillustrative and not restrictive. The scope of the disclosure should bedetermined by the appended claims and their legal equivalents, not bythe above description, and all changes coming within the meaning andequivalency range of the appended claims are intended to be embracedtherein. It is obvious to those skilled in the art that claims that arenot explicitly cited in each other in the appended claims may bepresented in combination as an embodiment of the present disclosure orincluded as a new claim by a subsequent amendment after the applicationis filed.

The various embodiments of present disclosure are applicable to variouswireless access systems including a 3GPP system, and/or a 3GPP2 system.Besides these wireless access systems, the various embodiments of thepresent disclosure are applicable to all technical fields in which thewireless access systems find their applications. Moreover, the proposedmethod can also be applied to mmWave communication using an ultra-highfrequency band.

1. A method performed by a user equipment (UE) configured to operate ina wireless communication system, the method comprising: receiving asynchronization signal/physical broadcast channel (SS/PBCH) block amonga plurality of SS/PBCH blocks; and acquiring synchronization based onthe SS/PBCH block, wherein the SS/PBCH block comprises a primarysynchronization signal (PSS), a secondary synchronization signal (SSS)and a physical broadcast channel (PBCH), wherein a plurality ofcandidate SS/PBCH blocks related to the plurality of SS/PBCH blocks areincluded in a half frame, and wherein information related toquasi-co-located (QCL) relation between the plurality of SS/PBCH blocksis received through a system information block (SIB)4.
 2. The method ofclaim 1, wherein the information related to QCL relation indicates oneof: 1, 2, 4 or
 8. 3. The method of claim 1, wherein the informationrelated to QCL relation being received through the SIB4 corresponds toell re-selection.
 4. The method of claim 1, wherein an index of theSS/PBCH block is determined based on the information related to QCLrelation and the plurality of candidate SS/PBCH blocks.
 5. The method ofclaim 1, wherein a number of the plurality of candidate SS/PBCH blocksand a number of bits included in the PBCH are determined based on asubcarrier spacing (SCS) for the plurality of SS/PBCH blocks.
 6. A userequipment (UE) configured to operate in a wireless communication system,the UE comprising: a transceiver; and at least one processor coupled tothe transceiver, wherein the at least one processor is configured to:receive a synchronization signal/physical broadcast channel (SS/PBCH)block among a plurality of SS/PBCH blocks; and acquire synchronizationbased on the SS/PBCH block, wherein the SS/PBCH block comprises aprimary synchronization signal (PSS), a secondary synchronization signal(SSS) and a physical broadcast channel (PBCH), wherein a plurality ofcandidate SS/PBCH blocks related to the plurality of SS/PBCH blocks areincluded in a half frame, and wherein information related toquasi-co-located (QCL) relation between the plurality of SS/PBCH blocksis received through a system information block (SIB)4.
 7. A methodperformed by a base station configured to operate in a wirelesscommunication system, the method comprising: obtaining a synchronizationsignal/physical broadcast channel (SS/PBCH) comprising a primarysynchronization signal (PSS), a secondary synchronization signal (SSS)and a physical broadcast channel (PBCH); and transmitting the SS/PBCHblock, wherein the SS/PBCH block is included in a plurality of SS/PBCHblocks, wherein a plurality of candidate SS/PBCH blocks related to theplurality of SS/PBCH blocks are included in a half frame, and whereininformation related to quasi-co-located (QCL) relation between theplurality of SS/PBCH blocks is transmitted through a system informationblock (SIB)4.
 8. A base station configured to operate in a wirelesscommunication system, the base station comprising: a transceiver; and atleast one processor coupled to the transceiver, wherein the at least oneprocessor is configured to: obtain a synchronization signal/physicalbroadcast channel (SS/PBCH) comprising a primary synchronization signal(PSS), a secondary synchronization signal (SSS) and a physical broadcastchannel (PBCH); and transmit the SS/PBCH block, wherein the SS/PBCHblock is included in a plurality of SS/PBCH blocks, wherein a pluralityof candidate SS/PBCH blocks related to the plurality of SS/PBCH blocksare included in a half frame, and wherein information related toquasi-co-located (QCL) relation between the plurality of SS/PBCH blocksis transmitted through a system information block (SIB)4.